Bogus check engine light
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,490
Likes: 8
Bogus check engine light
Anyone ever had the check engine light come on and discover it was a nothing afterwards? It came on in my C5 today and everything else seems just fine. No messages on the DIC, everything under the hood looks OK, engine runs perfect, etc.
Man I hate to take it to the dealer but I sure wouldn't want to break something.
Man I hate to take it to the dealer but I sure wouldn't want to break something.
Heel & Toe
Joined: Jan 2005
Posts: 19
Likes: 0
From: tega Cay sc
Engine check light
I have had that happen twice. Read the owners manual, did not raise any flags. Cleared by itself. The second time I did check the codes and I was getting PCM amd ICM communication error. Cleard them and have not had any problems. If it comes back, I will probably have it checked out. 
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Check your codes. You will have at least one in the PCM category. mark it down and reset it....resetting it will kill the CE light.
The check engine light will come on any time an emissions-related problem is detected. This could range from the simple, like a loose gas cap, to something more severe, like a misfire. If the light is on steady, it is not a severe problem, it may not affect how the engine runs.
If the light is flashing, that indicates a more serious problem.
The check engine light will come on any time an emissions-related problem is detected. This could range from the simple, like a loose gas cap, to something more severe, like a misfire. If the light is on steady, it is not a severe problem, it may not affect how the engine runs.
If the light is flashing, that indicates a more serious problem.
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
Originally Posted by VetteSiNz
Check your gas cap ... maybe it's just loose.
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Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,490
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Originally Posted by Stock Man
Check your codes and post them here.
Race Director
Joined: Nov 2003
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From: Mustang OK
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
Originally Posted by Stock Man
Check your codes and post them here.
Also, you should post the model year of your car as there have been some changes and additions to the DTCs (Diagnostic Trouble Codes) through the years.
Comments by Y2Kvert4me above are right on. Don't totally rule out the gas cap yet though. The cap seal can deteriorate overtime and if it does not seal properly, the cap will need to be replaced. If the cap is not sealing properly, it could cause failure of some of the evaporative emission (EVAP) systems tests which would set the Check Engine Light and DTCs. However, this is all speculation for now. Hopefully you will know more once you run the on-board diagnostics. Good luck with the fix.
Burning Brakes
Joined: May 2004
Posts: 1,080
Likes: 2
Mine comes on sometimes especially during the first 10 minutes of running. It's been doing it for the past 5,000 miles. I just re-set it. The car runs beautifully, gets fantastic gas mileage and the performance is as good as it always has been. l'm thinking mine is caused by one of the oxygen sensors. I'm not prepared to take the car to the shop. I know they are going to present me with a large bill! As long as everything seems fine and there are no probs with the e/test I'm leaving it alone. Good luck with yours.
Drifting
Joined: Apr 2004
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From: Jacksonville Florida
Team Owner
Joined: Sep 1999
Posts: 34,062
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From: Evans, GA
Jim,
Two weeks after I bought my 04 C5 the CEL came on and I called the dealerships repairshop. They said being it in and I did. After a 30 minute wait I was told that there were no codes and to return if it happened again. About 3 months later, I gassed up and left the service station and then the CEL illuminated. I pulled into a parking place and checked the gas cap. It was not tight so I removed and replaced it. The CEL went out. Checked the codes after I got home and guess what; no codes.
Maybe your situation is the same.
Two weeks after I bought my 04 C5 the CEL came on and I called the dealerships repairshop. They said being it in and I did. After a 30 minute wait I was told that there were no codes and to return if it happened again. About 3 months later, I gassed up and left the service station and then the CEL illuminated. I pulled into a parking place and checked the gas cap. It was not tight so I removed and replaced it. The CEL went out. Checked the codes after I got home and guess what; no codes.
Maybe your situation is the same.
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,490
Likes: 8
Originally Posted by 1Patriot
Jim,
Two weeks after I bought my 04 C5 the CEL came on and I called the dealerships repairshop. They said being it in and I did. After a 30 minute wait I was told that there were no codes and to return if it happened again. About 3 months later, I gassed up and left the service station and then the CEL illuminated. I pulled into a parking place and checked the gas cap. It was not tight so I removed and replaced it. The CEL went out. Checked the codes after I got home and guess what; no codes.
Maybe your situation is the same.
Two weeks after I bought my 04 C5 the CEL came on and I called the dealerships repairshop. They said being it in and I did. After a 30 minute wait I was told that there were no codes and to return if it happened again. About 3 months later, I gassed up and left the service station and then the CEL illuminated. I pulled into a parking place and checked the gas cap. It was not tight so I removed and replaced it. The CEL went out. Checked the codes after I got home and guess what; no codes.
Maybe your situation is the same.
That is EXACTLY what happened. Tightening my original gas cap did no good. I bought a new one and bingo...the CEL went out.Thanks to GrayC5 and VetteSiNz for posting the procedure and the codes.
