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Old 03-17-2009, 09:20 PM   #1
Sinister Evil
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Default Check engine light ON

2006 C6 Z51. and after 65,000 miles my check engine light came on. I have no serious mods on the car anymore except for B&B exhaust and Vararam intake. What should I do besides take it to a mechanic with a OBD reader? Could it be a bad sensor. I keep up with all the maintenance. Suggestions? Guidance? What to do?

Last edited by Sinister Evil; 03-17-2009 at 09:20 PM. Reason: mistake
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Old 03-17-2009, 09:28 PM   #2
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If you have OnStar you could ask for a diagnosis from the code. If not, then someone with a code reader is the only option. I think Autozone might do free code reading if there is one near you. Or there is always the dealer. Good luck, let us know what it is.
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Old 03-17-2009, 09:30 PM   #3
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Auto Zone has a scanner that they will let you use for free. This will also reset the light. You can also reset the Check engine light be disconnecting the positive battery cable. Leave it disconnected for around 15 minutes and this will also reset the light. You will have to fix your windows if you disconnect your battery also.
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Old 03-17-2009, 09:35 PM   #4
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I also have a 2006 Z51- 30'000 miles Just had a check engine light.

It was a Evaporation canister for the Emission system. Fixed -Light is gone.

No reason given for it to fail. Took it to the Dealer where I bought it
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Old 03-17-2009, 10:03 PM   #5
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I bought a $20 OBD II and it threw one code. It is the throttle position 1 performance code P0121. What to do? When I turned the car on again the check engine light was NOT ON but when I plugged in the OBD II it threw that one code P0121.

Suggestions? What do I have to fix? I don't want to erase the code until I address the problem.
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Old 03-17-2009, 10:11 PM   #6
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Here is some reading material but I'm thinking a trip to the dealer is at hand:

http://www.obd-codes.com/p0121
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Old 03-18-2009, 09:23 PM   #7
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I never cleared the code, but the check engine light hasn't come on. Thanks RickT. I'm off to the dealer on Saturday morning just to make sure....since my car is out of warranty I'm sure they are going to try to make some $$ at the dealer.
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Old 03-18-2009, 09:36 PM   #8
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Take a dozen bagels or donuts, it can make a difference especially on a Saturday. Good luck.
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Old 03-18-2009, 09:44 PM   #9
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Quote:
Originally Posted by Sinister Evil View Post
I bought a $20 OBD II and it threw one code. It is the throttle position 1 performance code P0121. What to do? When I turned the car on again the check engine light was NOT ON but when I plugged in the OBD II it threw that one code P0121.

Suggestions? What do I have to fix? I don't want to erase the code until I address the problem.
On the throttle body there are two variable resistors which report throttle blade angle. They are wired so that one reads 0 ohms at full closed and maximum ohms when full open while the other reads 0 ohms at full open and maximum at full closed. This is to give a sanity cross check to the ECM in case one fails shorted or open, and allows the car to continue to be drivable. These variable resistor sensors, called TPS (Throttle Position Sensor) are replaceable parts, available at most auto parts stores for a few dollars. It isn't necessary to replace the entire throttle body.

These are wear parts. Internally, there is an arm with a conductive brush that moves over a resistive substrate. With repetitive use, the brush wears down and the resistive substrate wears away. Eventually, the contact becomes noisy, intermittant, or fails entirely. The ECM throws the code when this happens. Sometimes you can extend the life of the sensor by using a product called Quietrol to clean and lubricate the resistive substrate. But that's a temporary fix at best. The correct fix is to replace the TPS.
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Old 03-18-2009, 09:48 PM   #10
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Quote:
Originally Posted by RedRider1 View Post
Auto Zone has a scanner that they will let you use for free. This will also reset the light. You can also reset the Check engine light be disconnecting the positive battery cable. Leave it disconnected for around 15 minutes and this will also reset the light. You will have to fix your windows if you disconnect your battery also.
Well, it'll reset the light until you hook the battery back up anyway.

This old wives' tale just will not die, will it? There are a number of conditions which will reset a CEL, depending on which particular code caused it. Disconnecting the battery isn't one of them.
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Old 03-18-2009, 09:53 PM   #11
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Did you recently add Z51 badges?

There are some who believe the addition of them will throw a code
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Old 03-19-2009, 11:27 AM   #12
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First: Congrats on getting great use out of your car. 20,000 miles/year = . Second: Run her to Autozone or the dealer to retrieve the code. You have no choice but to find out what you're up against...
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Old 03-19-2009, 11:34 AM   #13
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Here's my story -

Went to my local friendly Chevrolet Dealer (R.K.) here in Virginia Beach and told them CEL (Check Engine Light) was on. I asked the service writer to read the code. He was more than happy to; we plugged his OBDII scanner in and we were rewarded with "P0174" "Bank 2 System Too Lean."



This appears to be a good thing and is likely caused by a random hiccup due to my CAI and Cat-Back exhaust. We decided to clear the fault via the scanner and see if it returns. I somehow doubt it will (soon anyway). So in light of this I just went out and purchased a basic OBDII scanner with read and erase capability (cheap - actron PocketScan Plus $59.00). This way I can just clear it without driving all over town next time.
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Old 03-19-2009, 11:36 AM   #14
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My advise listen to ShopDogs advise, with the amount of miles on your car you are due sooner or later to change out your TPS.
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Old 05-02-2009, 12:26 PM   #15
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yep!! Thank you all for advising me on the TPS. Where can I get tps sensors and how do I replace them? Are they near/inside the throttle body?
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Old 05-02-2009, 12:41 PM   #16
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My CEL just came on last week and it was a P0171 + P0174 code.To much air in or something.The AUTO ZONE scanner could not turn the light off,the GM one at the dealer did. Check your gas cap and add dry gas in case you got a batch of bad gas somewhere which would set the light off.
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Old 07-02-2010, 07:18 PM   #17
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Fixed!! I replaced the gas pedal and the CEL was gone after two starts. Then it came back on after about 3 months.......I bought a new TB with TPS and DONE!! No CEL for 5 months. If you throw enough $$ at these cars they run great!!!! I luv my 'vette!!
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Old 07-02-2010, 07:26 PM   #18
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Quote:
Originally Posted by 08crm View Post
My CEL just came on last week and it was a P0171 + P0174 code.To much air in or something.The AUTO ZONE scanner could not turn the light off,the GM one at the dealer did. Check your gas cap and add dry gas in case you got a batch of bad gas somewhere which would set the light off.
your CEL is likely due to the MAF sensor mis-reading the airflow entering the engine. had similar issues early on. using metal a/c tape, taped off the holes in the bumper support in front of the engine compartment as well as the seam where the front fascia meets the trim at the bottom front of the air box. no more issues and that was 3 years and 25k miles ago.

Last edited by dpigguy; 07-02-2010 at 07:27 PM. Reason: spelling
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Old 07-02-2010, 07:33 PM   #19
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Quote:
your CEL is likely due to the MAF sensor mis-reading the airflow entering the engine. had similar issues early on. using metal a/c tape, taped off the holes in the bumper support in front of the engine compartment as well as the seam where the front fascia meets the trim at the bottom front of the air box. no more issues and that was 3 years and 25k miles ago.
I was thinking and wondering if I could put some duct tape over that area.I had my light on before I heard about the disruption of air flow because of the design.Now there's a TSB on that code!
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Old 07-02-2010, 07:42 PM   #20
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Quote:
Originally Posted by 08crm View Post
I was thinking and wondering if I could put some duct tape over that area.I had my light on before I heard about the disruption of air flow because of the design.Now there's a TSB on that code!
BG had me tape mine up and the CEL issue went away. Here's a picture of the area you need to address:

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