[Z06] "Check Engine" light, Help!
Thread Starter
Advanced
Joined: Aug 2004
Posts: 55
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From: Granite Bay CA
"Check Engine" light, Help!
My "check engine" light came on a month or so ago. I made an appointemet at my local dealer and by the time I got it over there, the light had gone out. I assumed it must have been a gas cap problem??? Well, yesterday, it came on again and I have not added gas since the last problem. I plan to call the dealership, but wondered if any of you have had a similar situation. Thanks. 
Racer
Joined: Sep 2001
Posts: 434
Likes: 1
From: Clermont FL
You need to pull codes, but if it comes and goes there is a good chance its a leaning mixture, just on the border of minimum lean.
If you have a non stock air filter it could be that or an air leak in the intake.
If you have a non stock air filter it could be that or an air leak in the intake.
Team Owner
Joined: Oct 2001
Posts: 56,381
Likes: 79
Originally Posted by rbartick
Post # 31 in the FAQ sticky does not cover moving back and forth within each module to see multiple codes in the module (if they exist).
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Safety Car
Joined: Dec 2002
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From: PA
The H at the end means it's history. In other words, it was a problem now it's not. I had the same thing happening to my 02 Z, and mine turned out I had a bad #7 fuel injector. Get it into the shop and they can check it out for you. 
Le Mans Master
Joined: Jun 2001
Posts: 7,331
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From: Admit Nothing, Deny Everything, Make Counter Accusations.
Originally Posted by MAJ Z06
Can you explain how to do this, or find it, and I will add it.
Once the IPC displays "manual diagnostics" you may select a particular module by pressing the options button to go forward or the trip button to go back. You may find more than one code on a module. To scroll through multiple codes in a module press gages to move forward or fuel to go back within the module. If you want to erase a code press reset.
To exit the diagnostic mode at any time, press E/M.
Burning Brakes
Joined: Jun 2004
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From: I'm not quite middle aged and I only own one gold chain! San Jose CA
Originally Posted by Billco
Codes show - PO171 H, and PO174 H. Lean left bank and lean right bank. Does the H mean the problem is in the past. If so, why would it come and go?
These are also the codes that will be displayed if you have put most of the aftermarket intakes such as the Halltech, Vararam, Donaldson Blackwing, etc. The PCM isn't able to adjust for the increased volume of air coming through the intake and reads it as a lean condition, which it is technically speaking. Just thought I would toss it out there in case you had put a new intake on.
There are other issues that can cause these codes to pop up of course, but just wanted to mention this one since it is a common issue and easily resolved.
Le Mans Master
Joined: Jun 2001
Posts: 7,331
Likes: 518
From: Admit Nothing, Deny Everything, Make Counter Accusations.
Originally Posted by Scott04Z
The PCM isn't able to adjust for the increased volume of air coming through the intake and reads it as a lean condition, which it is technically speaking.
Thread Starter
Advanced
Joined: Aug 2004
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From: Granite Bay CA
Originally Posted by Scott04Z
These are also the codes that will be displayed if you have put most of the aftermarket intakes such as the Halltech, Vararam, Donaldson Blackwing, etc. The PCM isn't able to adjust for the increased volume of air coming through the intake and reads it as a lean condition, which it is technically speaking. Just thought I would toss it out there in case you had put a new intake on.
There are other issues that can cause these codes to pop up of course, but just wanted to mention this one since it is a common issue and easily resolved.
There are other issues that can cause these codes to pop up of course, but just wanted to mention this one since it is a common issue and easily resolved.
3rd Gear
Joined: Sep 2005
Posts: 3
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From: Los Angeles CA
I had the same issue a few months ago after installing a Vavaram Intake System and letting it rip on the highway. According to the owners manual, it can be due to a change in the gas consumption or a better word for it, poor gas mileage. The light went away after a day or so once I began to get higher miles per gallon.
Melting Slicks
Joined: Nov 1999
Posts: 2,372
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From: N Cal
Originally Posted by Billco
I did have an aftermarket intake installed about a year ago. The first time the "check engine" light came on of about a month ago. I don't drive it much (about 100 miles/month) but wouldn't the light have come on sooner, if it was caused by new intake?
Thread Starter
Advanced
Joined: Aug 2004
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From: Granite Bay CA
Originally Posted by l2vette
A good road trip will relearn the mods you have made to the stock unit. I would suggest the last lemans series race for thr C6R in monterey this saturday, A good road trip is why we own these awesome toys!!!
Burning Brakes
Joined: Jun 2004
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From: I'm not quite middle aged and I only own one gold chain! San Jose CA
Originally Posted by Billco
I did have an aftermarket intake installed about a year ago. The first time the "check engine" light came on of about a month ago. I don't drive it much (about 100 miles/month) but wouldn't the light have come on sooner, if it was caused by new intake?
It depends on how you drove the car. It is possible that it wouldn't throw the code if you were babying it. It happens when the PCM goes into the closed loop program as rbartick mentioned previously.
