Strange "Check Engine"
Thread Starter
Cruising
Joined: Mar 2015
Posts: 14
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Strange "Check Engine"
Something strange happened with my car. Periodically itself illuminated "Check" and after some time it goes out. There is no connection between the style of driving and this inscription. Usually it is on a day or two. While checking engine the computer says "rich mixture", but why this happens is not clear. There is no other mistakes in the computer. Oxygen sensors are in order. Friend proposed to rewrite the engine control program in the main computer. I'm not sure that he is right. What do you think about my problem?
Thanks in advance.
Thanks in advance.
Last edited by Mr.Moscow; Aug 7, 2015 at 04:19 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
PLEASE post the specific DTCs that are being displayed.
I personally would CLEAR all the DTCs and when it throws the CEL (Check Engine Light) illuminates, PRESS RESET to clear any messages in the DIC and (without turning the ignition off) pull up the code reader in the DIC and see what NEW DTCs are being displayed.
NO!!!!!!!! It is NOT wise to attempt to reprogram the PCM to attempt to FIX this issue. If there is something wrong, FIX what is wrong. If your engine is running properly and you have modded your engine and have NOT had it properly RE-TUNED,, then YES! The tuner can correct this issue by adding more fuel or removing fuel (depending on the exact fueling error causing the DTC to pop!)
Please list the entire DTC! ~~~~ EXAMPLE: P-0171 C ~~~ Fuel Trim System Lean Bank 1
C = CURRENT. Meaning happening NOW
H = HISTORY. Happened sometime in the past but is not currently happening
I personally would CLEAR all the DTCs and when it throws the CEL (Check Engine Light) illuminates, PRESS RESET to clear any messages in the DIC and (without turning the ignition off) pull up the code reader in the DIC and see what NEW DTCs are being displayed.
NO!!!!!!!! It is NOT wise to attempt to reprogram the PCM to attempt to FIX this issue. If there is something wrong, FIX what is wrong. If your engine is running properly and you have modded your engine and have NOT had it properly RE-TUNED,, then YES! The tuner can correct this issue by adding more fuel or removing fuel (depending on the exact fueling error causing the DTC to pop!)
Please list the entire DTC! ~~~~ EXAMPLE: P-0171 C ~~~ Fuel Trim System Lean Bank 1
C = CURRENT. Meaning happening NOW
H = HISTORY. Happened sometime in the past but is not currently happening
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
I'm going thru the same thing. Check engine light comes on randomly and then goes out in a few days or so. All codes are listed as H for history and no new / current codes. Anne mentioned it seems to come on sometimes after getting gas. Any ideas guys?
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
UPDATE: OK, did as told and cleared them all and shut it off and restarted it. With it running, no check engine light.
Hopefully that does it. If it comes back on repeat again or some way to check things now?
Thanks for the assist, this stuff drives me nuts. A very short trip indeed.
Hopefully that does it. If it comes back on repeat again or some way to check things now?
Thanks for the assist, this stuff drives me nuts. A very short trip indeed.
Last edited by Mr. Jean; Aug 13, 2015 at 08:35 PM.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
So that's why the engine light went out and doesn't come back on now, when I started it back up later?
This may take awhile then, as Anne's driving it to work daily. So I'll have to tell her to tell me when it comes back on and hope it's on the way home. If it is, for her to leave it running when arriving home and tell me, so I can look at the codes, correct?
If correct, then look at the code list to see what the problem is?
I'm thinking of buying a Code reader to help with some of this later.
Guess I'm going to have to learn this 21st century stuff, if I'm going to keep these 2 Corvette's.
Thanks for your helping me with this.
This may take awhile then, as Anne's driving it to work daily. So I'll have to tell her to tell me when it comes back on and hope it's on the way home. If it is, for her to leave it running when arriving home and tell me, so I can look at the codes, correct?
If correct, then look at the code list to see what the problem is?
I'm thinking of buying a Code reader to help with some of this later.
Guess I'm going to have to learn this 21st century stuff, if I'm going to keep these 2 Corvette's.
Thanks for your helping me with this.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
I've also got a Z06 and a Tahoe, so I'm thinking of getting this one to learn this stuff and perhaps be able to help others around here on CF.
Any thoughts on this one?
http://www.summitracing.com/parts/anm-cp9580a
Any thoughts on this one?
http://www.summitracing.com/parts/anm-cp9580a
Melting Slicks
Joined: Apr 2009
Posts: 2,479
Likes: 36
Strange "Check Engine"
Since you've also got a Z06 and a Tahoe, just get a Tech 2 and be done with it. You'll be glad you did. A Tech 2 clone can be had for less than $400. You would have the same scanning and two way diagnostics as a GM dealer.
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Melting Slicks
Joined: Sep 2011
Posts: 2,256
Likes: 543
From: Appleton WI
You likely provided an important piece of information about the light coming on after getting fuel. If your gas cap is not properly seated or the seal is worn out, it can trigger the check engine light.
As has been requested, either you or your wife needs to pull the codes before shutting off the engine the next time the light turns on. It is an easy process using the DIC buttons.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
In my last post I gave a link for one. Is this what you mean or your thinking something better? If so, can you provide a brand, stock # or link to the one you think will be better?
Does the one your mentioning have easy to understand programs, that I can use to guide me to the problems and offer things to do to fix things myself? Thanks for the assist.
I love CF and all you guys that help out.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
Mr Jean
You likely provided an important piece of information about the light coming on after getting fuel. If your gas cap is not properly seated or the seal is worn out, it can trigger the check engine light.
As has been requested, either you or your wife needs to pull the codes before shutting off the engine the next time the light turns on. It is an easy process using the DIC buttons.
You likely provided an important piece of information about the light coming on after getting fuel. If your gas cap is not properly seated or the seal is worn out, it can trigger the check engine light.
As has been requested, either you or your wife needs to pull the codes before shutting off the engine the next time the light turns on. It is an easy process using the DIC buttons.
In the mean time, I did replace the DRL bulb for her.
One down and one to go.
If it is the cap, do I need a special one or just get any new one? Can you get a new seal separate? Thanks
Melting Slicks
Joined: Apr 2009
Posts: 2,479
Likes: 36
As I mentioned, I know close to nothing on this computer stuff.
In my last post I gave a link for one. Is this what you mean or your thinking something better? If so, can you provide a brand, stock # or link to the one you think will be better?
Does the one your mentioning have easy to understand programs, that I can use to guide me to the problems and offer things to do to fix things myself? Thanks for the assist. I love CF and all you guys that help out.
In my last post I gave a link for one. Is this what you mean or your thinking something better? If so, can you provide a brand, stock # or link to the one you think will be better?
Does the one your mentioning have easy to understand programs, that I can use to guide me to the problems and offer things to do to fix things myself? Thanks for the assist.
I love CF and all you guys that help out.http://www.careucar.com/wholesale/gm...e-tis2000.html
It isn't harder to use than any other OBD2 scanner on the market IMHO. But, you can at least perform all GM specific tests and commands.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
Thanks Cybermind, I'll give it a look and do some homework on it.
I guess it just depends on how much I want to do myself and how much i want to spend on it all.
So far, it's just been this one problem on the C5 and it may be just a gas cap, we'll see. No codes or real problems on the rest of the rides to date.
Thanks again for the assist, you've been very helpful.
I guess it just depends on how much I want to do myself and how much i want to spend on it all.
So far, it's just been this one problem on the C5 and it may be just a gas cap, we'll see. No codes or real problems on the rest of the rides to date.
Thanks again for the assist, you've been very helpful.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
The seal is not sold separately. You can easily inspect the seal and perhaps it is still good but has some debris on it or the sealing surface.
As far as a replacement cap I bought the GM OEM one because I wanted the leash/tether that helps prevent loosing it. The aftermarket ones I was able to find did NOT have the leash. About $18 from the auto parts places and double that from a Stealership.
As far as a replacement cap I bought the GM OEM one because I wanted the leash/tether that helps prevent loosing it. The aftermarket ones I was able to find did NOT have the leash. About $18 from the auto parts places and double that from a Stealership.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
Update: Light came back on again. Got these codes from it.
P0171 and P0174. Code list says they're Fuel Trim system lean on banks 1 & 2.
Is this the code you guess got when having a bad cap or is this a different problem. Any help/info appreciated here. Thanks
P0171 and P0174. Code list says they're Fuel Trim system lean on banks 1 & 2.
Is this the code you guess got when having a bad cap or is this a different problem. Any help/info appreciated here. Thanks
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
You have an air leak after the Mass Air Flow (MAF) Sensor. Could be a loose clamp on the air plumbing, or a crack in any of the air plumbing tubing or the hoses on the PCV system may be dry rotted and cracked. That allows unmetered air to get in and the system runs lean as a result. That is why both sides show lean.
Should be pretty easy to inspect all of those and find the air leak and repair.
Should be pretty easy to inspect all of those and find the air leak and repair.
I'll have to search for some diagrams to trace this stuff down. Thanks again.
Last edited by Mr. Jean; Aug 15, 2015 at 07:52 PM.
Safety Car
Joined: Dec 2006
Posts: 3,623
Likes: 316
From: Sparks, Nevada
Well, I've put on a new GM gas cap, just to be sure she never gets that code, as it looked tired in the gasket area.
To be sure to pass the smog test without codes, I took the Haltech Stinger and K&N filter off and put the GM stocker back on, with a new Fram filter. Anne will never miss that BIG hp loss anyway.
It passed smog this morning and no codes or check engine light.
So it was probably an inlet leak in the MAF/ Haltech area or the oil from the K&N filter deal.
All I care about is it's running fine again. A happy wife, as the saying goes.....
Thanks again to everyone, for their suggestions / help.
Now back to the important stuff, MY rides.
To be sure to pass the smog test without codes, I took the Haltech Stinger and K&N filter off and put the GM stocker back on, with a new Fram filter. Anne will never miss that BIG hp loss anyway.
It passed smog this morning and no codes or check engine light.
So it was probably an inlet leak in the MAF/ Haltech area or the oil from the K&N filter deal.
All I care about is it's running fine again. A happy wife, as the saying goes.....
Thanks again to everyone, for their suggestions / help.
Now back to the important stuff, MY rides.
Last edited by Mr. Jean; Aug 19, 2015 at 02:28 PM.