: Check Engine Light



GAGS-V
06-08-06, 03:35 PM
Anybody have this come on? Mine did today while driving normally down the road. I called on-star and they ran their diagnostic check yet were unable to find out what it may be. Any ideas out there BEFORE I take to my wonderfull dealer?

StealthV
06-08-06, 03:40 PM
Could be hundreds of different things. Within the past few weeks, have you recently installed or worked on your air filter, intake tube, aftermarket exhaust or headers?

And the easy one - is your fuel filler cap on tight?

GAGS-V
06-08-06, 03:46 PM
Well, I hope it's not hundreds of things (shudder with the dealer). No I have not done any of the items you have mentioned in the past few weeks. Now on that gas cap item I will have to go check on:) Thanks for your help....

50 4Ever
06-08-06, 03:51 PM
Check out this old document, there should bew a way to display the codes. On my Corvette there is a way to display and reset the codes when necessary without the use of an ODB-II Scan Tool.

http://www.cadillacfaq.com/faq/answers/codes.html

On-Star should have been able to tell you the code(s). Good luck.

:thumbsup:

RedGalant2k1
06-08-06, 04:43 PM
What is the car doing? Rougher idle? Poorer Gas mileage? Noise?

Florian
06-08-06, 05:09 PM
I get em all the time....its usually emissions related and theyll clear after a while. I got sick of em so I bought EFILive to clear em



F

JOEYCTS-V
06-08-06, 05:26 PM
Onstar is a joke when it comes to reading codes. Everytime I called them they said "It's the PCM"....WTF does that mean? No help whatsoever. :bigroll:

2004ctsv
06-08-06, 05:36 PM
I've used OnStar to determine what caused the check engine light.
When I asked, the person gave me the code which I looked up on the FAQ.
It was pretty simple and straight forward. The code was something like XX007 and indicated that I had a vacuum leak.

It worked for me.

T

urbanski
06-08-06, 06:57 PM
autozone will scan the code
look it up on the FAQ

Barak
06-08-06, 07:08 PM
Greg,

Stop by and I will pull the code for you. If you don't remember how to get here, PM or call me for directions.

GAGS-V
06-08-06, 09:58 PM
Hey guys thank you for all the help! You are all the best, way more helpfull than any dealer.

Here's another twist in this tale. The check engine light comes on and stays on for two start-drive-stop trips and then on the way home it goes off! What to make of that?

StealthV
06-08-06, 10:15 PM
Catalytic converter or O2 sensor near death, fuel trims either too rich or too lean (clean your MAF sensor), air leak somewhere in the intake track, exhaust leak at the cat-back joint and a hundred other things... :)

Speculation is easy; get the code(s) and know.

Barak
06-09-06, 12:12 AM
Hey guys thank you for all the help! You are all the best, way more helpfull than any dealer.

Here's another twist in this tale. The check engine light comes on and stays on for two start-drive-stop trips and then on the way home it goes off! What to make of that?

The system is simply following regulation. In order for a confirmed trouble code to clear itself, the diagnostic for the particular component or system must run and pass on three consecutive trips in order to extinguish the light and clear the code. If the check engine light is illuminated on a fully OBD-II compliant vehicle, it will always be for something emission related. Regulation does not allow the light to be illuminated for any other reason.

50 4Ever
06-09-06, 01:21 AM
The system is simply following regulation. In order for a confirmed trouble code to clear itself, the diagnostic for the particular component or system must run and pass on three consecutive trips in order to extinguish the light and clear the code. If the check engine light is illuminated on a fully OBD-II compliant vehicle, it will always be for something emission related. Regulation does not allow the light to be illuminated for any other reason.

So, are you saying that a Corvette is not ODB-II compliant? I had the check engine light come on and stay on. The code I was throwing was a P0704 Clutch Switch Circuit, nothing to do with emissions.

:confused:

Barak
06-09-06, 10:41 AM
While a Corvette is obviously OBDII compliant, if you were to pick apart any OBD system one would find errors where the manufacturer didn't completely follow regulation due to misinterpretation, programming error, oversight...a million reasons. The clutch switch circuit may be one of those things that was overlooked by CARB during certification, or a type A or B diagnostic that was later changed to a type C during the next model year. It is also quite possible that the clutch switch is in fact emission related since the ECM may use the switch input to alter engine management, therefore qualifying it as emission related and requiring that the MIL be illuminated if a failure occurs. It's always better to error on the side of caution and light the MIL rather than the other way around. If the MIL isn't lit when it should be then the manufacturer is really in big trouble.

GAGS-V
06-09-06, 12:08 PM
Thanks for your help Barak! As always, you're a positive asset to this forum. You certainly know much more about these codes and issues than me. If it act weird today I will post again later. Are you going to the So-Cal meet on Sunday in Long Beach?

Barak
06-09-06, 12:34 PM
Thanks for the kind words. I will try to make it on Sunday, but I'm leaving for Michigan on Monday and it might be a bit hectic this weekend. If I can make it maybe we can cruise there together.

ctsvett
06-10-06, 01:15 AM
dont mess with Barak on OBD stuff... That guy Knows his $hit.

Reed

GAGS-V
06-10-06, 02:54 PM
Barak, Let me know what time you may be leaving. Let's see if that works.