The GAS CAP code!!!!!!!!!!!!!!

The dreaded GAS CAP code!!!

I see many posts here about how to fix ( the dreaded GAS CAP) EVAP codes. Today I am going to educate you as to the functions and diagnostics involved in Evaporative Emissions issues and what the codes mean.
Lets start off with the whys.
The purpose of the Evaporative Emission system is to limit the amount of Hyrdocarbons released into the atsmosphere.
Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid ON, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid OFF, fresh air is drawn through the vent solenoid and the vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.
So in a nut shell if the control module senses a leak in the system that will allow more than a prescribed amount of fuel vapors escape, the module will illuminate the yellow engine light also know as the Check Engine (CEL)or Service Engine Soon (SES) light.
Depending on the year, make and model of your vehicle, this leak could be as small as .020” or twenty thousands of an inch ( a hole equal the point of a sharpened pencil lead)

Now with any diagnosis, the first thing we what to do after verifying the concern is to check the codes. This can be done at just about any chain auto parts store or if you own a code scanner, you can do it yourself.
DO NOT CLEAR THE CODE!!!!!!!!!!!!!!!!!!!! This is your key to finding out what is going on……we will clear the code after we repair the vehicle.

EVAP codes are considered either TYPE A or TYPE B codes..which in simple terms means the control module must see 1 failure for a TYPE A or 2 or more back to back failures for a TYPE B before the SES or CEL light is turned on.
Lets take a look at the codes and what they mean
P0440 or a P0455 – This is a Large leak indication or as people call it “The GAS CAP code”
This is a TYPE B code. Usually the code is caused by the gas cap being left off or loose after a refuel. This code could also be caused by any failure of the EVAP system that will cause a large leak.
P0442 – This is a Small leak indication.
This is a TYPE A code. This indicates a leak as small as .020”.
This code needs some serious diagnosis and knowledge of the system to find and repair the leak. Usually specialized equipment will be used to identify the leak.

P0446 – This indicates there is a restriction or blockage of the Vent Solenoid.
This is a TYPE B code. Any thing that prevents the venting of the EVAP system will set this code…usually dust and debris in the Vent solenoid or a damaged vent hose will cause this.

The other EVAP codes (P0443,449 etc) are electrical codes related to various components of the EVAP system.
Electrical codes need some good diagnostic skills, knowledge of the system and some specialized equipment.

With any car repair concern, there is a logical flow to follow when trying to identify what is going on..here in the GM world, we call it Strategy Based Diagnostics or 7 simple steps to diagnose a concern.
As always, verifying the concern and then doing a thorough visual inspection is key. It’s amazing how quickly a problem can be fixed by just the results of a visual inspection.
Now getting back to EVAP concerns….once you have identified the problem, you must come up with a repair, then a verification that the vehicle is repaired properly.
With EVAP leaks, usually a large leak is caused by a loose gas cap. Reinstalling the cap and clearing the code will be a quick remedy. But remember that you must always verify your repair..this could include professional intervention…(EEK!!!!!!!!!PAYING SOMEONE TO WORK ON MY CAR…..NO WAY!) . Well yes, this may be necessary..I have seen many times where people have come in to have a EVAP code cleared and refuse diagnosis only to have the light come back on…then blame me for the light coming back on…(then post on AF how the “stealership” did not fix their car).
But this isn’t a rant, this is information on what is going on.
Repair verification could include EVAP system testing with specialized equipment to verify that there are no leaks present..I personally check every EVAP system for leaks even if I find the customer left the gas cap loose…this insures that there are no other problems with the system that would cause the customer a trip back to see me. Far too many times have I seen someone tighten a gas cap and clear a code only to have the vehicle come back a few days later with a “real” EVAP leak…masked by a loose gas cap.
If you have a SES or CEL light caused by an EVAP concern and you have the code cleared and it comes back on after a few days….get to your local repair shop ( I recommend your local dealer with factory trained technicians) and have the system tested and repaired properly.
If you want to DIY the repairs, feel free, there are plenty of resources on the internet, but just don’t jump in and replace parts…educate yourself on the system and perform some diagnosis…many times a part will not fix the concern…
Good Luck
GMM
:2cents:

GMMerlin (http://www.automotiveforums.com/vbulletin/member.php?u=75615) vbmenu_register("postmenu_4358002", true);
I know stuff


Yes you do my friend, Yes you do.... Keep on doin the :2cents:

what "specialized equipment" do you use to help with your diagnosis of the P0442 code????

what "specialized equipment" do you use to help with your diagnosis of the P0442 code????
I use an EEST (Evaporative Emissions System Tester ) which has a flow meter and can interject smoke into the system to identify leak sources

I use an EEST (Evaporative Emissions System Tester ) which has a flow meter and can interject smoke into the system to identify leak sources


yea I have that code on my truck now...... is there any possable way to fix this without such equipment maybe even make shift equipment of some sort???

The problem with the P0442 code is it can be set by a leak as small as .020 on your truck.
If you find a better way let us know

Your the best Merlin!!

I, like many unfourtunate souls, have the dreaded "gas cap code" issue.
For me, it's a P0440, which from your post, tells me I have a gross leak, which makes me happy...it should be easier to find that way......

At this time, I'd like to point out that I suffer from ASEphobia, that is an irrational fear of somebody else working on my truck. I often sit in the waiting room, reading that issue of sports illustrated from 1986 (the one with Icky Woods on the cover), and wondering what the hell is going on in there.

Several bad experiances with professional mechanics in my youth have damaged me for life!!! (a few long stories I won't bore you with)

My question is this, what can the average guy do to seek out the gross leak? I've gone through the whole system, and checked for obvious cracks, loose hoses, and such, but have obviously found nothing. (already put a new gas cap on).

My sending unit is currently on the fritz. My gas gauge goes back and fourth often like an old analog multimeter, could that have something to do with it?

can a bad air filter can cause a P0440 (internet myth?)

Thank you O' wise master of automobile (yeah, I'm sucking up...but I need help!!)

Your the best Merlin!!

I, like many unfourtunate souls, have the dreaded "gas cap code" issue.
For me, it's a P0440, which from your post, tells me I have a gross leak, which makes me happy...it should be easier to find that way......

At this time, I'd like to point out that I suffer from ASEphobia, that is an irrational fear of somebody else working on my truck. I often sit in the waiting room, reading that issue of sports illustrated from 1986 (the one with Icky Woods on the cover), and wondering what the hell is going on in there.

Several bad experiances with professional mechanics in my youth have damaged me for life!!! (a few long stories I won't bore you with)

You don’t suffer from ASEphobia, you just took your vehicle to a mechanic instead of a technician :shakehead

My question is this, what can the average guy do to seek out the gross leak? I've gone through the whole system, and checked for obvious cracks, loose hoses, and such, but have obviously found nothing. (already put a new gas cap on).


There could be many causes of the leak, I would look at the tank seal for the sender, vent solenoid to see if it is closing (may be operating electrically, but not mechanically)
Do you have any gas leaks around the tank area?
Without specialized equipment such as the EEST I use, finding leaks on the system is difficult…no impossible, just difficult.
Most of the time it is knowing where to look and what you are looking for.

My sending unit is currently on the fritz. My gas gauge goes back and fourth often like an old analog multimeter, could that have something to do with it?


The PCM does use the level sender for tank volume so it knows when to run the test, it uses the FTPS to determine if there is a leak.

can a bad air filter can cause a P0440 (internet myth?)


NO! That’s what I love about the net…someone will post something that someone else will believe…who knows, I could be a 12 year old hiding behind a computer, giving car advice

Thank you O' wise master of automobile (yeah, I'm sucking up...but I need help!!)

No sucking up needed…usually cash does the trick, usually in large unmarked bills..I’m partial to Ben Franklin myself:rofl: :rofl:

Does anyone know the best way to fix a p0446 code? its the evap code circuit malfunction code.

Does anyone know the best way to fix a p0446 code? its the evap code circuit malfunction code.
[QUOTE][P0446 – This indicates there is a restriction or blockage of the Vent Solenoid.
This is a TYPE B code. Any thing that prevents the venting of the EVAP system will set this code…usually dust and debris in the Vent solenoid or a damaged vent hose will cause this.
/QUOTE]

GMM

Greetings,

If I use the gas cap that came with the truck - everything is fine - no error codes. However I purchased a locking gas cap by the industry standard (Stant). It seems to fit/work perfectly - except about half the time - about half the tank to empty - I'll get a "loose gas cap" error on the DIC. Then regardless of what I do to tighten it more - later on (maybe an hour, a day or three days later) - I'll get the yellow "check engine light" going on. If I put the original cap back on - then the error light quits.

But it doesn't always do this - only maybe 50% of the time. The Stant cap only goes so tight then has a "clutch" effect so it can't be tightened more. This did this since brand new - and it hasn't changed over the last 2 years. Also - I notice I get better gas mileage with the locking cap on compared to the regular cap. As an example - in highway driving I get 23 with the locking cap - and maybe 20 or 21 at the most - with the factory cap.

Input and knowledge is desired :)

I have a 2005 Avalanche. I forgot to put the gas cap on for my last tank. I got a computer message a few times, but it was raining so I was not inclined to go outside and tighten the cap. I then got the "check engine" light.

What I did notice, however, was the better gas milage. This is like the post before. I am very compulsive to reset my gas milage checker with every tank. That is the mode I leave it on all the time. With the current tank now down to 1/4 full, I have been getting 22.0mpg, which is the record best I have ever gotten. With regular use (i.e., gas cap on), I would have been getting about 18.3 mpg.

The question....is there any real harm in leaving the gas cap loose since I obviously am getting considerably better milage? I live in one of the big towns where all gasoline is diluted with 10% ethanol (that is another gas milage story....the day that started, milage went down from about 20.0 to 18.3).

I drive mostly lots of easy miles on the freeway...very little stop and go.

Car is still under warranty so I am not too concerned about getting code reset.

Thanks!

I have a 2005 Avalanche. I forgot to put the gas cap on for my last tank. I got a computer message a few times, but it was raining so I was not inclined to go outside and tighten the cap. I then got the "check engine" light.

What I did notice, however, was the better gas milage. This is like the post before. I am very compulsive to reset my gas milage checker with every tank. That is the mode I leave it on all the time. With the current tank now down to 1/4 full, I have been getting 22.0mpg, which is the record best I have ever gotten. With regular use (i.e., gas cap on), I would have been getting about 18.3 mpg.

The question....is there any real harm in leaving the gas cap loose since I obviously am getting considerably better milage? I live in one of the big towns where all gasoline is diluted with 10% ethanol (that is another gas milage story....the day that started, milage went down from about 20.0 to 18.3).

I drive mostly lots of easy miles on the freeway...very little stop and go.

Car is still under warranty so I am not too concerned about getting code reset.

Thanks!

All gasoline sold in the US is 10% ethenol

All gasoline sold in the US is 10% ethenol
Not true.....10% ethanol is used only in major metropolitan areas that do not attain certain air quality attainment goals. For example, in Texas, I believe this is only in the Houston and Ft. Worth/Dallas metropolitan areas. In the rest of the state, there is no ethanol dilution of gasoline.

As stated before, the day ethanol showed up at the pumps last spring (to replace the much better burning MTBE which was eliminated because the Dems in Congress would not allow the oil companies limited liability on spills - although MTBE was previously mandated by Congress in the first place), my car gas milage dropped about 6%.

Not true.....10% ethanol is used only in major metropolitan areas that do not attain certain air quality attainment goals. For example, in Texas, I believe this is only in the Houston and Ft. Worth/Dallas metropolitan areas. In the rest of the state, there is no ethanol dilution of gasoline.

As stated before, the day ethanol showed up at the pumps last spring (to replace the much better burning MTBE which was eliminated because the Dems in Congress would not allow the oil companies limited liability on spills - although MTBE was previously mandated by Congress in the first place), my car gas milage dropped about 6%.

Dude, the last energy bill from congress banned the use of MTBE in the U.S.
Gasoline needed a replacement oxidation agent so the fuel refineries are using 10% ethanol in place of MTBE.

Not a big issue, but FYI, reformulated gasoline (i.e., the diluted E10 stuff that replaced MTBE) is only used in areas that do not meet government polution goals. This is mainly just California and the East Coast with some few major cities in between (e.g, Ft. Worth/Dallas and Houston). Fortunately, the rest of our country does not have to use this stuff. The travesty is that the political establishment forced this on us to make the corn growers and other ag interests happy. The oil companies also charge more for it (much higher distribution costs because it can't be put in the pipelines, but has to be trucked and mixed at the local distribution centers) and we get lower milage than before. Overall, MTBE was a much better answer, povided society learns not to be stupid and spill it (legitimate ground water polution issue).

See link below from EPA showing where reformulated gas is required. The rest of of the country still gets good 100% unadulterated gasoline molucules (minus a few additives).


http://www.epa.gov/otaq/rfg/whereyoulive.htm

Hey Man, you may want to check the date on that table. Sept, 2005. I'm pretty sure Merlin is right and pretty much all of our gas has some level of EToH up to 10% now.

[quote][P0446 – This indicates there is a restriction or blockage of the Vent Solenoid.
This is a TYPE B code. Any thing that prevents the venting of the EVAP system will set this code…usually dust and debris in the Vent solenoid or a damaged vent hose will cause this.
/QUOTE]

GMM

Yeah I have that code also But I replaced the rear vent solenoid and gas cap looked over the hoses all the way to the intake manifold which looked good...is there something else that code could indicate? Could it be the cannister itself and if so are they expensive? I have a 2002 Silverado 5.3 Z71. I have cleared the code 3 times now and have tried something different each time to try and clear it...it has always set at 68-70 Mph or whenever I'm on the interstate.. Any help is VERY much appreciated.

Yeah I have that code also But I replaced the rear vent solenoid and gas cap looked over the hoses all the way to the intake manifold which looked good...is there something else that code could indicate? Could it be the cannister itself and if so are they expensive? I have a 2002 Silverado 5.3 Z71. I have cleared the code 3 times now and have tried something different each time to try and clear it...it has always set at 68-70 Mph or whenever I'm on the interstate.. Any help is VERY much appreciated.


I'm getting the same code on my 01 5.3 Z71. I called the dealership and they said that there is a kit available to Replace/prevent this from happening. (If you replace the vent solenoid with same one, you will eventually deal with this again) I can't remember what he said the kit cost, but he quoted me roughly $300 for them to take care of everything.


I was wondering how hard it would be to install this yourself. I'm not exactly sure where the vent solenoid is located, or if any special tools are necessary. I have a friend that's a certified mechanic so hopefully I can talk him into helping me out, because I'd rather not dish out 300 smackaroos if it's something anyone with some mechanical ability can figure out.

Hey people........I have a 2000 pontiac grand prix se..........code po446 is set meaning blockage or restriction of the vent solenoid......also on start up the gas gauge will go to the full mark then after 1 or 2 minutes will decline to the empty mark and the low fuel light will come on........will fixing the code po446 cure the fuel sending unit problem ??????.......or will replacing the fuel sending unit and fixing the blockage or restriction of the vent solenoid cure the whole problem.....:banghead: ..I need direction ............THANKS.....Also where is the vent solenoid located ????????

Before you replace the Evap Canister read this

Subject: DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Service Engine Soon (SES) Lamp Illuminated (Replace Hose/Evaporative Emission (EVAP) Canister Vent Asm) #02-06-04-037A - (02/02/2005)
Models: 1999-2003 Chevrolet Silverado Models
1999-2003 GMC Sierra Models
--------------------------------------------------------------------------------
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 02-06-04-037 (Section 06 -- Engine/Propulsion System).
--------------------------------------------------------------------------------
Condition
Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the instrument panel SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.

Cause
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

Correction
After following the Service Manual diagnostic P0446 and determining that the EVAP canister vent valve is the cause of the SES light, replace the existing EVAP canister vent hose assembly with a new assembly, P/N 15086429. This new assembly has an enhanced filtering capability and a filter element that can be easily removed and cleaned. To ensure correct installation, follow the procedure below.

Raise the vehicle. Suitably support the vehicle.
Disconnect the EVAP canister vent valve electrical connector.
Disconnect the vent valve pipe at the EVAP canister.
Remove and retain the EVAP canister vent valve bracket mounting bolt.
Disengage, from the underbody, the two vent valve pipe clips securing the pipe to the underbody.
Remove and discard the complete EVAP canister vent hose assembly.
Position and secure the new assembly to the underbody using the existing hole and mounting bolt.
Tighten
Tighten the bracket mounting bolt to 12 N·m (106 lb in).

Install the two vent valve pipe clips into the existing underbody holes.
Connect the vent valve pipe to the EVAP canister.
Connect the EVAP canister vent valve electrical connector.
Lower the vehicle.
When properly installed, the new EVAP canister vent hose assembly will be positioned outboard of the original installation location. This new location provides clearance for accessing the filter element for cleaning purposes. To access the filter element, disengage the filter cover to valve locking finger by gently lifting the finger upward while simultaneously rotating the filter body clockwise. After approximately 45 degrees of rotation, the filter can be disengaged from the valve by gently pulling outward. The filter cover can then be removed and the filter element and body can be washed with soap and water. Prior to reinstalling, ensure that the body and filter element are dry.

Parts Information
Part Number 15086429 Hose Asm-Evap Emis Cnstr Vent

hello
't was great to read all the science behind the code. and many cries for how to fix it without paying large bill to your stealership, or lesser to your mechanic, etc.
so, i am an addicted do it yourself first, feed the dealer if you have no other choice person. so here's my fix: i replaced the fuel tank cap with one from shucks, it's six bucks, has pressure relieve valve in it, and is made in usa. also, pretty red color. no, it does not have a cord that holds it from being lost. then i flushed fuel system with a can of seafoam on full tank. had it done some 4 mths ago.
that's it. 12 bucks damage. no special tools, smog injectors, and such. god bless the guy on internet who posted "can't tell how many $100 jobs have we charged for simple re-snugging or replacement of the gas cap". excellent tip.
oh, something else. i do not buy cheap gas and gasohol. it's only chevron, texaco, and occasinally shell. just my opinion. you bet THAT has to do some with the code.

i am only speck of dust at the mighties of this thread feet, but humbly say must i that ethanol is not in ALL gas and not in ALL metro areas. reason i know this is that about 2 yrs ago, i have contacted every major gasoline retailer here in the pacific northwest. as you have noticed, virtually every lower end gas station has a white tag on dispenser saying: this gasoline contains 10% ethanol. chevron, texaco, shell, bp, exxon, did not. so, me being me, i emailed them direct.
surprisingly, they did all reply! sometimes, from a very high level, from folks that manage half the country. so, chevron does not, texaco does not, shell does mostly, but not in some areas, exxon does not, bp varied. turned out to be, there are local regulations that do not permit use of ethanol. 'about that!
so, as a thought on the side, i do have better mpg on chevron gas. that comes from a dude that drove for almost a year with digital mpg/data gauge connected to OBD2 plug and mileage logged.
ethanol is virtually inescapable in corn producing states, where farmers bullied it into the law, to have their corn crops supported. i came across stories of folks driving to canada for non-ethanol gas purchases. on the surface, government was "concerned" about peoples welfare (does it ever?:naughty: ), but between the lines, the whole ethanol boom was initiated by huge pressure and lobbying from organized farmers.
even on the better left thought, folks drive to mexico to tank, as last time i checked, gas was around 2 bucks a gallon there. too far to drive to venezuela though, with it's 17 cents a gall.:lol2:

All gasoline sold in the US is 10% ethenol not true if that was trus then all pumps would have to say 20% eth as im a gas hauler and we slpash blend eth here on the east coast there fore it would be E20

Well I had a P0449 code , engine light on for about a week.After a $430.00 est I decided I would try it myself.Had a thought after reading all the threads & decided to leave cap off for a day in our 100* heat .The light went off.I'll watch it & see what happens.
:smile:
laneman
2006 Silverado 4x4
72000 mi

My truck had the gas cap code. It began shorty after I installed a cheap aftermarket fuel pump. It also began to have problems starting, like fuel pressure was bleeding off. The engine light seemed to come on when the tank was low on fuel only. I replaced the cap and the fuel regulator. No change. I replaced the pump with a quality replacement pump and all symptoms were fixed. I didn't read through all the posts, but I don't recall seeing any that indicated the pump can cause this code. In my case the cheap pump was the cause.

I live in Nebraska and we can choose between Regular 87 Octane, 10% Ethanol 89 Octane, or Premium 91 Octane. I see this is most places that I travel.

My 2006 Chevy Impala has the "Tighten Gas Cap" blinking. I brought it into work where we did the trouble codes and used the scanner to find out the codes and that the Canister Vent Solenoid was leaking by way to EVAP smoke test. So I bought a new Soleniod,installed it, cleared the codes and the thing is back on the next morning. Can anyone tell me what else could be wrong in the system to bring up the 0445 code? The smoke clearly came out around the solenoid, hopefully there isn't something stupid like a loose hose.

Hi im new on here. I started my Silvy last night and heard a clicking noise i havent heard before for a few minutes. then it went away. 1 minute later the "SES" service engine soon light came on....Still no clicking noise and havent heard it since then. so I went to autozone pulled the code P0446.

My question...The clicking sound I heard..is that the EVAP Vent Solenoid being fried...I still seem to be having a problem locating it. 01 silverado 2wd reg cab short box. 26 gallon tank. All parts on the fuel delivery look new especially the gas tank. just bought the truck last year. looks like to me they had a problem with this before and decided to replace everything before the warranty went up...i bought it with 77,000 miles on it and now it has 92,000. I did add a half bottle of AMSOIL gas additive 3 days before. and a oil change with AMSOIL xl 5w-30 a/c delco oil filter. :runaround:

Hey folks im really sorry to post off topic but i need help right away!! my friend has a 2003 lancer. I am not familiar with newer mitsubishis. she was on the highway and her car shut off. we pushed it to burger king. I checked her oil and it was empty, so i assume the car shut off because of that. we put in 3 qts and tried again but it still would not catch. it is turning over like a champ tho. please help! is there something i need to do to reset the sensor or something? why wont it turn on? lancers do have that safety feature right? and is there a chance she just destroyed the engine? thanks alot! you will definitely help me score some points and just help out another person

Here is bulletin for your DTC P0446


[hr]
[/align]
#02-06-04-037D: DTC P0446 (Restricted/Blocked Evap Vent Path) Set, Check Engine Light On (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly and Add/Relocate Filter Box Using Service Kit) - (Apr (http://chevroletforum.com/forum/#) 16, 2008) [/align]
http://gsi.xw.gm.com/image_en_us/gif/000/999/999/999999995.gif [align=left]



Subject:
DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Check Engine Light On (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly and Add/Relocate Filter Box Using Service Kit)



Models:
1999-2007 Chevrolet Silverado (Classic) Models




1999-2007 GMC Sierra (Classic) Models




2007-2008 Chevrolet Silverado Models




2007-2008 GMC Sierra Models

[hr]

This bulletin is being revised to add new style pickups to the models and update the correction information to include a new location for the filter box. Please discard Corporate Bulletin Number 02-06-04-037C (Section 06 Engine/Propulsion System).
[hr]

Condition
Some customers whose vehicles (http://chevroletforum.com/forum/#) are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the check engine light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.
Cause
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.
Correction (1999-2007 Classic (http://chevroletforum.com/forum/#)/Old Style Models)
After following the published SI diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the MIL light, replace the existing EVAP canister vent valve assembly with a new assembly. This new assembly is a sealed unit that is designed to be vented through a remote filter box. To ensure correct installation, follow the procedures below.

1999-2003 Model Year (Use Service Kit P/N19152345)
Raise the vehicle (http://chevroletforum.com/forum/#). Suitably support the vehicle.
Disconnect the EVAP canister vent valve electrical connector, if equipped.
Disengage the two vent valve pipe clips securing the pipe to the underbody. Remove the clips from the underbody and discard.
Disconnect the vent valve pipe at the EVAP canister.
Remove and retain the EVAP canister vent valve bracket mounting bolt.
Remove the complete EVAP canister vent valve assembly with bracket attached and discard.
http://gsi.xw.gm.com/image_en_us/gif/000/001/848/1848436.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=1848436)

Important:The new canister vent valve will be installed in a new location, outside of the frame.
Position and secure the new valve assembly to the frame bracket on the outside of the frame using the existing hole and mounting bolt.
Tighten
Tighten the bracket mounting bolt to 12N·m (106lbin).
Connect the vent valve pipe to the EVAP canister.
Install the two vent valve pipe clips into the existing underbody holes.
Connect the EVAP canister vent valve electrical connector, if equipped.
Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
http://gsi.xw.gm.com/image_en_us/gif/000/002/094/2094032.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=2094032)

Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
Raise the transmission and reinstall the transmission support.
Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
Lower the vehicle.

2004-2007 Model Year (Use Service Kit P/N19152349)
Raise the vehicle. Suitably support the vehicle.
Disconnect the EVAP canister vent valve electrical connector.
Disconnect the canister pipe from the vent valve.
Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket. Discard the old valve.
Cut back the existing canister pipe approximately 51mm (2in) to remove the quick connect end.
Crew Cab Short Box Shown Below, Other Configurations Similar
http://gsi.xw.gm.com/image_en_us/gif/000/001/848/1848440.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=1848440)

Extended Cab Short Box Shown Below, Other Configurations Similar
http://gsi.xw.gm.com/image_en_us/gif/000/001/848/1848441.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=1848441)

Install the new canister vent valve to the fuel tank clip or mounting bracket.
Cut bulk 5/8" heater hose to a length of approximately 76mm (3in). Install the hose between the vent valve and the canister pipe and secure using clamps.
Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
http://gsi.xw.gm.com/image_en_us/gif/000/002/094/2094032.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=2094032)

Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
Raise the transmission and reinstall the transmission support.
Connect the EVAP canister vent valve electrical connector.
Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
Lower the vehicle.
Correction (2007-2008 New Style (http://chevroletforum.com/forum/#) Models)
After following the published SI diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the MIL light, replace the EVAP canister vent valve assembly and relocate the remote filter box. To ensure correct installation, follow the procedures below.

Use Service Kit P/N19152349
Raise the vehicle. Suitably support the vehicle.
Disconnect the EVAP canister vent valve electrical connector.
Disconnect the vent valve pipe quick connect from the canister.
Either cut the existing valve vent pipe and leave the remaining section of pipe in the vehicle or remove along with the valve.
Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket.
Cut back the existing canister pipe approximately 51mm (2in) and retain the pipe for use with new valve.
Connect the canister pipe quick connect to the canister.
2500 Crew Cab Short Box Shown Below, Other Configurations Similar
http://gsi.xw.gm.com/image_en_us/gif/000/001/848/1848441.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=1848441)

1500 Extended Cab Short Box Shown Below, Other Configurations Similar
http://gsi.xw.gm.com/image_en_us/gif/000/002/092/2092801.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=2092801)

Install the new canister vent valve to the fuel tank clip or mounting bracket.
Cut bulk 5/8" heater hose to a length of approximately 76mm (3in). Install the hose between the vent valve and the canister pipe and secure using clamps.
Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the passenger side area above the transmission.
Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
Remove the transmission heat shield, if necessary.
Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
http://gsi.xw.gm.com/image_en_us/gif/000/002/094/2094032.gif
http://gsi.xw.gm.com/si/images/tif.gif (http://gsi.xw.gm.com/si/showTif.do?image=2094032)

Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
Raise the transmission and reinstall the transmission support.
Reinstall the transmission heat shield.
Connect the EVAP canister vent valve electrical connector.
Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
Lower the vehicle.
Parts Information




Part Number

Description

Qty

Material Allowance


19152345 (1999-2003 Model Year)

Solenoid Kit, EVAP Emission Canister Vent Valve

1




19152349 (2004-2008 Model Year)

Solenoid Kit, EVAP Emission Canister Vent Valve

1




9438383 (5/8" X 25' roll)

Hose

Cut to Length

$10.80 USD ($22.59 CAD)


12337820 (10 per pack)

Tie-Strap

5

$3.80 USD ($4.55 CAD)


15620999 (10 per pack)

Clamp

2 (1999-2003)
or
4 (2004-2008)

$3.78 USD ($7.08 CAD) (1999-2003)
or
$7.56 USD ($14.17 CAD) (2004-2008)
Put unused material on shelf for future use.
Hope this helps you.when you finish let us know,what was wrong.

I discovered 3 - error codes P0442, P0443 & P0455 after taking my 03' Suburban 1500 LS 5.3L 2wd to get smoged. Went to my mechanic who did a smoke test found leaks on both (cracked vent/rollover valves) from the top of the fuel tank. Fuel tank replaced, $1,100 dollars later code P0455 came back after a week or two. Back to mechanic discovered bad contact where the wires connect to the molex connector to the canister purge control solenoid while moving wires around because it would work then not work. He ordered the connector, I replaced it myself. Took it back so he could clear the code. Code back (P0455) after a week. I replaced the gas cap with an OEM. Took it to my friend who read and cleared the code. Code was back after a couple weeks. Where do I look next? Please help I'm going crazy. I really need a DIY fix cause I'm running out of cash....

I discovered 3 - error codes P0442, P0443 & P0455 after taking my 03' Suburban to get smoged. Went to my mechanic who did a smoke test found leaks on both (cracked vent/rollover valves) from the top of the fuel tank. Fuel tank replaced, $1,100 dollars later code P0455 came back after a week or two . Back to mechanic discovered bad contact where the wires connect to the molex connector to the canister purge control solenoid while moving wires around because it would work then not work. He ordered the connector, I replaced it myself. Took it back so he could clear the code. Code back (P0455) after a week or two. I replaced the gas cap with an OEM. Took it to my friend who read and cleared the code. Code was back after a couple weeks. Where do I look next? Please help I'm going crazy. I really need a DIY fix cause I'm running out of cash....

the code p0455 comes back after a couple of weeks ???
this is strange.

my guess is the engine is running when you fuel up.

this would be a large leak in the venting system. if the code comes back all the time every day I would say it is a leak in the vent system.

every time the engine starts it goes thru the diagnostic test of the fuel vapor system. the vent solenoid could be sticking sometimes.

In the rust belt the fuel filler tube can rust through.

never fill the fuel tank all the way and park it. burn off excess fuel before parking. this is how these devices get messed up. the fuel gets into the charcoal cannister then black goo fouls the valves.

I do not gas up with the engine running. The code ma have come back sooner than 2 weeks. Any place specific I should check in the vent system?

I do not gas up with the engine running. The code ma have come back sooner than 2 weeks. Any place specific I should check in the vent system?

never fill the fuel tank all the way and park it. burn off excess fuel before parking. this is how these devices get messed up. the fuel gets into the charcoal cannister then black goo fouls the valves.

vent valve may need replacing. check the vent lines for black goo first.

the lines must be replaced or cleaned first or the vent valve may get fouled again.

My tahoe has been setting off the p0455 code. Took it to my mechanic yesterday, and I had to leave my car with him for 1day. I've changed my fuel filter and fuel pump last month. I've noticed my gas milage has been really bad, a full tank of gas would only last about three days.

My tahoe has been setting off the p0455 code. Took it to my mechanic yesterday, and I had to leave my car with him for 1day. I've changed my fuel filter and fuel pump last month. I've noticed my gas milage has been really bad, a full tank of gas would only last about three days.

with the gas mileage poor and loosing fuel over three days you must have a leak. check or I should say have someone check the fuel lines for leaks especially the lines near the vapor fuel canister. the return line will leak only when the engine runs. replacing the fuel pump you/they may have cracked the plastic lines. some do not remove and drop tank then the plastic gets broken ////VERY COMMON ///TIME IS MONEY ...

Hi,
I was driving my car this morning, an 01' Deville and on my DIC it gave me the message "Check Gas Cap." But, the SES light did not pop on. So, the first thing I did is tighten the gas cap. I normally get my gas in New Jersey as it's much cheaper than New York City. Jersey law prohibits to fill your own tank. So, it is always a gas jockey pumping the gas and putting your cap back on.

I did notice that my cap did not seem to be flush. So, I took it off and put it back in and made sure it clicked a few times. The SES light is not on and

I get the message "Check Gas Cap" when I start my car. I used my OBD II scanner and I did have the P0440 code.

But, still no SES light, just the message "Check Gas Cap." This happened this morning. So, perhaps it will simply take time for the system to reset itself.

Does anyone have any thoughts on why there is no SES light, the DIC says "Check Gas Cap?

Thanks for any help.

I have a 2009 chevy Silverado small leak code comes up even after the new gas cap from the dealer...did the smoke test could NOT find anything wrong or a leak what do I do??? please help! thanks

I need help :( 2009 Silverado small leak code did smoke test no leak found and purge valve was working replaced the gas cap from the dealer and still light comes on.... help please!

I need help :( 2009 Silverado small leak code did smoke test no leak found and purge valve was working replaced the gas cap from the dealer and still light comes on.... help please!

post the code number .

post the code number .

Po442

Po442

this code means the PCM has found that your fuel tank has a small leak when the vacuum test is performed. this can be the vapor canister/lines around the vapor canister/the fuel filler metal neck will rot and have small leak where it is secured at the fender/ these are some of the reported and common causes.

with the gas cap code , this would indicate a large leak. the other codes report that the vent valve is defective.

if the fuel pump was replaced then the gasket could be screwed up.

happy hunting..

this code means the PCM has found that your fuel tank has a small leak when the vacuum test is performed. this can be the vapor canister/lines around the vapor canister/the fuel filler metal neck will rot and have small leak where it is secured at the fender/ these are some of the reported and common causes.

with the gas cap code , this would indicate a large leak. the other codes report that the vent valve is defective.

if the fuel pump was replaced then the gasket could be screwed up.

happy hunting..

the truck is clean no rust and only has 70000 miles on it and has never had the tank massed with we went thru all the lines and no cracks or pinched hoses and didn't find any rusted out lines out of things to look at :( thanks anyway...

the truck is clean no rust and only has 70000 miles on it and has never had the tank massed with we went thru all the lines and no cracks or pinched hoses and didn't find any rusted out lines out of things to look at :( thanks anyway...

I would remove the vapor canister inspect the hoses/plastic /metal lines all in this area. the metal return line usually corrodes in this area. the fuel filler disconnect and drop down to check for holes at the bracket weld points.

the intake manifold has a line that goes to the vacuum valve . this line may have a leak crack ..

the truck is clean no rust and only has 70000 miles on it and has never had the tank massed with we went thru all the lines and no cracks or pinched hoses and didn't find any rusted out lines out of things to look at :( thanks anyway...

if you did check all these things I mentioned then my guess is the in tank fuel pump assembly pressure/vacuum sensor. this is part of the fuel pump unit.

If you have only this dtc p0442 then this is why I say this part.

the dealership if they have people that know what there doing should be able to test this component for proper operation rather than parts replacing at your expense.

your issue is a very small leak not pinched hoses or valves stuck open or plugged up.. this sensor maybe failing when sensing the vacuum.


looks like the 2009 has issues with this ..service bulletin is this
SB-10-06-04-001 01/01/2010
10034369
2010-11-08
Chevrolet/gmc/pontiac: intermittent mil/check engine light on, dtc p0442, p0446, p0451, p0452, p0453, p0454 or p0455 (install fuel tank pressure sensor cover). this condition may be caused by normal water accumulation or condensation bloc

Needs to be smoked tested by someone who knows what they are doing....

Short version 2012 Impala 100000 miles brought to dealership for repairs involving fuel gauge failure. Pick up car drove aprox 3 miles and got tighten gas cap message. Tighten cap everything seemed fine, two days later got second tighten gas cap message, checked cap everything seemed okay ,started car and now have engine light. Car is at dealership for diagnostic , so no code yet. Trying to determine what the dealership could have screwed up to cause code. Should note that this is second time car has been returned to dealership because of sloppy work ( also had problem with airbag light after engine repair that was done at same time)

Obviously, if the code was not there before, it's possible they caused it.....

Do you know exactly what was done? Was fuel sender replaced?

From the invoice, Internal faultwith fuel level sensor replaced faulty fuel level sensor

No problems prior to repairs Car rn ojt of gas due to level sensor notvreading correctly

Update code appears to be evap solenoid failure claim is it is coincidental to fuel level issue . Supposedly fuel level issue was masking. Solenoid problem. Doe this sou d probable or is the dealership jerking me around. Honestly my gut feeling is this is B.S. so any opinion would be appreciated.

Update code appears to be evap solenoid failure claim is it is coincidental to fuel level issue . Supposedly fuel level issue was masking. Solenoid problem. Doe this sou d probable or is the dealership jerking me around. Honestly my gut feeling is this is B.S. so any opinion would be appreciated.










they F'ed up the fuel tank venting system it is a leak a large leak they damaged the lines going to the fuel tank or they damaged the charcoal canister/ lines to that as well .. I am sure they WILL NOT reveal what the did improperly .

If they screw with you about this ,, post the dealerships name and how they screwed you .. also facebook ..

Update code appears to be evap solenoid failure claim is it is coincidental to fuel level issue . Supposedly fuel level issue was masking. Solenoid problem. Doe this sou d probable or is the dealership jerking me around. Honestly my gut feeling is this is B.S. so any opinion would be appreciated.

Fuel level sensor has nothing to do with the evap solenoid, and vice versa.....

The reason why I asked if the level sender was replaced, was because that means the evap system was opened, and this could cause a leak, possibly at the evap line, or more likely the o-ring between the gas tank and the fuel module was possibly pinched......

Tahnk for the imput. Pick car up today no further repairs done was quoted a price of $98 to replace inoperative evap vent solenoid. Told them I would get back to them about it. Asked what the code was and was told it was P0442 code. When I got the car back engine light was still on. I planned on bringing the car to an auto parts store to see if they could run code. Drove about 6-7 miles stopped at a different store for amoment and when I started the car again engine light was off. Engine light has stayed off and remote start is working again.

P0442 is not a solenoid code....it means there is a small leak somewhere in the entire system......

It could be the solenoid, if the solenoid is not sealing when turned off........

Coincidence that it failed(located on top front of engine) when working on the gas tank? Who knows?

but like I said, if there was no P0442 set before the work was done, chances are the leak is where they took the evap system apart, at the gas tank...

Fact they said, " Supposedly fuel level issue was masking. Solenoid problem." is total crap.....

If you have a small evap leak, the only sure way to find it, is to seal the system with a TECH II scan tool, and pressurize the system with a smoke machine.....where you see smoke, you find the leak....

the dealership created a leak in the fuel tank seal or the lines. dropping the fuel tank the charcoal canister can get cracked .

the 442 code could be a bad valve .. the fuel level if not between the 1/4-3/4 range the fuel evap system test will not be taken by the PCM .

block seal the line going to the evap vent valve see if you still get the 442 code.. I would check out the lines under there as you do this ..

449/446 codes are the ones most times indicating the vent valve the problem ...

leaks could also the the fuel fill pipe .. I did have that happen .. used some metal mender or marine-tex epoxy .. rust hole up on the pipe support flange ..

[quote=Simulacrum dwp;7206665]Tahnk for the imput. Pick car up today no further repairs done was quoted a price of $98 to replace inoperative evap vent solenoid. Told them I would get back to them about it. Asked what the code was and was told it was P0442 code. When I got the car back engine light was still on. I planned on bringing the car to an auto parts store to see if they could run code. Drove about 6-7 miles stopped at a different store for a moment and when I started the car again engine light was off. Engine light has stayed off and remote start is working again.[quote] ---------------------------------------------------------------------------------






could be the very cold temps caused the light to come on . the seal on the fuel tank may have seated properly stopping the small leak.

Ok so here is where I'm at now. Light came back yesterday afternoon. A friend who has a diagnostic checked it out and there is two codes P0443 and P0455. I am planning on contacted GM regarding this ( considering it was their dealship and mechanics that did the work incorrectly) any further advice would bve appreciated.

Both codes have to do with the purge valve or it's circuit.....

Simple way to check a purge valve, disconnect wire harness to purge valve, apply vac(use vac pump) to the end of the valve that goes to the evap system(not the end that goes to the intake)......vac should hold......now apply 12 volts and ground to valve(pink wire is usually the hot wire), and the valve will open and the vac will drop....

What usually happens is the vac doesn't hold and it leaks......or the solenoid does not open to purge the system when powered....