DTC P0442/97 jimmy 4.3 v-6 4X4

[DaVeMoE]

I've been reading some of the posts about this evap. emission control system leak detected (small leak) code. But I do not know where to start looking. I've found some info. that says it may be due to a gas tank leak or it may be an evap vent solenoid problem (TSB #77-65-08). I have not had the chance to look for my self yet,but before I do, Does anyone have any real world probable spots to look at (without having to go to the dealer or a repair shop...you know it's the old, do I pay a shop or keep the money at home for food/bills/etc. thing). Seriously though I would like some pointers on the most likely spot this trouble might be. The truck has approx. 120 K on it and I thought that it had a small gas tank leak on it when I bought it along with that darn fuel level sending unit problem,but that's been like that for almost 7-8 months and this "new" light just came on the day before yesterday. Thanks Dave

[MT-2500]

code 442 is a code for a small vacuum leak in the evap emission system.
The fuel tank and evap system has to hold vacuum without leaking off.
A small vacuum leak can be the vacuum lines or solenoids or tank or sensor gas cap.

If you have a gas leak in the tank that may be the problem.
Find and repair that leak.

Always give the cap 3 clicks.

First thing besides the gas leak is to check/test gas cap or replace with a GM OEM gas cap.

If that does not do it check all hoses and lines and anyplace that can leak vacuum.
A scanner and a smoke machine is sometime required to check and test and find the hard to find leaks or problems.
MT

[MT-2500]

In the suburban forum there is a post on gas cap code repair info.
MT

[DaVeMoE]

MT ,Thank-you very much for the timely respose/info.
I will look around and post results as soon as I find any.

[MT-2500]

You are welcome.
And let us know how it goes.
MT

[DaVeMoE]

Just a quick update; I went to my local dealer to check there price to start to diagnose the problem,he said they get $90. to start,He also told me the same things to check as you did MT. I also bought a new GM gas cap from them(very reasonable at only $25 regular price)as my cap's o-ring was very cracked, itr also looked to be original.The parts guy also told me that the vent control valve was also around $25. I'll give the cap acouple of drive cycles to see if the code clears and if not I may very well start thinking about replacing the tank/sending unit as well. (will update as info. comes along) Thank-You once again!

[MT-2500]

Sometimes they are slow on clearing the code on there own.
Give it some time.
The tank sensing unit on has the pressure on it.
Vent solenoid and vent lines will be under hood with vent lines back to tank.
If cap does not do it check the vent solenoid.
Good luck
And let us know how it goes.
MT

[DaVeMoE]

Hey MT, well it's been about a week since I installed the OEM gas cap and the SES light is still on. I was under the truck tonight changing my u-joints and I was looking at the filler pipe, charcoal canister,and lines,they all "look ok", so I guess my next step is to look for the numbers on the vent solenoid (as per TSB #77-65-08) to see if I got one of the bad one's. I still will eventually replace the tank and sending unit,but I wonder that since it does not leak gas could it leak pressure?! Just wanted to get in touch and let you know what's going on! I appreciate the help you have given!! Thank-you once again.

[MT-2500]

You are welcome.
Maybe but not usually on the fuel pump module seal.

I would clear code with a scanner and see if it comes back and also check tank vacuum readings and see how fast vacuum is leaking down.
Good Luck
MT