Question:Warnings

I have a 1999 Z71 Ext.Cab 5.3 w/ 118,000. Service Engine Light came on last night and stays on. Can it be read by something to determine what the problem is, or am I screwed?

I have a 1999 Z71 Ext.Cab 5.3 w/ 118,000. Service Engine Light came on last night and stays on. Can it be read by something to determine what the problem is, or am I screwed?

You can take it someplace like Autozone and the will read/clear it for free. I forget the name of the scanner we need to read the codes ourselves, but someone else here will tell us.

So your sayin if i take my truck to Autozone and get them to hook it up to thier diagnostic thinger they will either clear it as an error or read the problem indicated...for free....?

Autozone checks codes for free indeed, from what I hear.

yep, so should napa, pepboys, carquest, advance auto, ect.....

I have a 1999 Z71 Ext.Cab 5.3 w/ 118,000. Service Engine Light came on last night and stays on. Can it be read by something to determine what the problem is, or am I screwed?


You are not screwed.....what has happened is the computer has seen a problem related to one of its inputs or outputs and turned on the light.
Autozone or one of the other chain auto parts store can read the code for you.
Post the code here and we can help you figure out what is going on from there

I am having the worst luck. My service engine soon light came on and has stayed on for almost three days. I go to Autozone this morning like you guys suggested, and as I am pulling into the parking lot, the service engine soon light goes out!

Autozone says they can't read it if the light is not lit. Now, I have to wait until the damn thing comes on again. Unfortunately, I might not get another chance....whatever is wrong might just go out next time instead of giving me another warning. Whew, this is frustarting!

WHAT ??????????
They can to read it. Its a stored code. The guy you talked to must have just got fired at Mcdonalds and hired as a auto tech.
1999 Is OBD2 computer system and it is stored there and is still there

I am having the worst luck. My service engine soon light came on and has stayed on for almost three days. I go to Autozone this morning like you guys suggested, and as I am pulling into the parking lot, the service engine soon light goes out!

Autozone says they can't read it if the light is not lit. Now, I have to wait until the damn thing comes on again. Unfortunately, I might not get another chance....whatever is wrong might just go out next time instead of giving me another warning. Whew, this is frustarting!


Codes are stored in history, The code reader should be able to pull the code.

Okay guys, I got the code read. it is a P171 and a P174 which the Chevy guide say is Fuel Trim Lean in Bank 1 and 2. The book says it could be anything ranging from an unseated oil cap or stick to a loose hose. I know it is not the oil stick or cap, and I can't find any particular hose that seems to be unsealed. I am pretty sure it is a seal or loose hose though because within 5-10 minutes of run time it goes away. Enough time for whatever is loose to seal up. Any suggestions?

Okay guys, I got the code read. it is a P171 and a P174 which the Chevy guide say is Fuel Trim Lean in Bank 1 and 2. The book says it could be anything ranging from an unseated oil cap or stick to a loose hose. I know it is not the oil stick or cap, and I can't find any particular hose that seems to be unsealed. I am pretty sure it is a seal or loose hose though because within 5-10 minutes of run time it goes away. Enough time for whatever is loose to seal up. Any suggestions?

Do you want the dianogstic chart for P0171 & P0174? If so leave me a private message with your e-mail address. I will need to know your engine code letter (Probally VIN "R" 0r "T"). I can send it in JPG format.

If the code doesn't make sense it could also mean that you just have a bad sensor.

If the code doesn't make sense it could also mean that you just have a bad sensor.

Which one?

You can buy an AUtoTap which works off a Palm Pilot or Laptop for aroun 299

Hey Merlin, what's the fuel cap code? I can't remember and don't have my manual handy.

-slacker

Which one?

Yeah, that's the problem. There are so many sensors feeding that computer. If the code says you've got a fuel mix problem you'd need to check the sensor that detects the fuel mixture. I don't have the maintenance manual so I couldn't tell you. You can start by pulling and cleaning the sensors one by one. I believe the fuel misture sensor is on the exhaust manifold and it is probably rusted/corroded. Cleaning may not be practical. Those sensors can be kind of expensive, also.

Hey Merlin, what's the fuel cap code? I can't remember and don't have my manual handy.

-slacker


There is no "fuel cap code"
There are codes for the evap system depending on if it is a small of large leak. Either one can be caused by a loose gas cap.
The problem is most people automatically assume that it is the cap and won't go as far as to test the system integrity.
Case in point..I get called to the Service Managers office on morning..in his office is a customer who is cussing mad..been to 2 different dealers for a reoccuring SES light on his Grand Am...everytime they have told him it was a loose cap.
I take the car and do some diagnostics..found the seal on the top of the tank pinched causing a leak.
Replace the seal and clear the code..no more problems..plus gained a new customer :grinyes:
Too many times people automaticly assume without checking the basics first.

Too many times people automaticly assume without checking the basics first.

I wish more people took the time to actually do their job. It seems too often that people take vehicles in and describe the problem and the dealer either doesn't believe them or pawns it off as not their problem.
I'm an electrician and often have to trouble shoot other peoples work when a problem occurs. Like you said Merlin, take the time to look it over and you will find usually a small easy to fix solution for the problem. Then come out looking like a hero because you take a little more pride in your work than the person before you.
Sorry for the little rant, but I believe it to be true.

seems like i read here that the fuel cap code was similer to what he suggested maybe the 174???????????jj

seems like i read here that the fuel cap code was similer to what he suggested maybe the 174???????????jj

P0171 and 174 are fuel trim lean codes...mostly caused by a vacum leak.
I have found a few intake gaskets leaking (vacum not coolant) causing this also a crack in the plastic upper intake can cause this.

Which one?

I wouldn't jump to the conclusion that the sensor is bad but with the mileage it's probable...the sensor would be the O2 sensor (tells the computer whether the fuel mix is lean or rich)

You missed the humor in that post

You missed the humor in that post

Yea looks that way. In my own defense it didn't appear funny just odd.

Chevy place read the codes P0171 and P0174 and then checked all hoses and seal etc.. They found nothing. They say they are 99.9 % sure it is the fuel pump. Thoughts?

Bump

Did anybody find out what the problem was? I have this same issue. The exact same codes! Looked over everything. No one can find it.. errr!!!! Always seems to run fine though.. Just that SES light drives me nuts!!

Are you using a K&N filter?
I am having the same prob. and codes.
Replaced the fuel filter and the light came back.
I was told that the oil from the K&N will cause the mass air flow sensor to get dirty.

Did anybody find out what the problem was? I have this same issue. The exact same codes! Looked over everything. No one can find it.. errr!!!! Always seems to run fine though.. Just that SES light drives me nuts!!


Are you using a K&N filter?
I am having the same prob. and codes.
Replaced the fuel filter and the light came back.
I was told that the oil from the K&N will cause the mass air flow sensor to get dirty. My fuel economy has also went to the dumps.
Going to clean the MAF, and put a paper filter back in. Hope it works, and is not the o2 sensors, they are not cheap. Let me know if the same is for you.