A few months ago I purchased a 2005 C6. About a month ago the check engine light came on. The dealership has had the car more then I have since then. The have replaced the sensors. replaced sensors wire harness, replaced the wires. The dealership can't figure it out. The mechanic says to try harness extenders because the original owner installed headers but it;s not factory so they won't do it. Anybody ever had this happen? Any suggestions?

 

There are a few different codes these sensors can throw, tell us which codes you have to help narrow it down?

 

The headers are the problem because they move the O2's away from the stock location. You could try heat wrapping the headers to hold more heat in. It might help. Or you could have a tuner to tune the car open loop.

I'm assuming you are having issues with the upstream O2's, the ones that control your air fuel ratio. If it's the down stream O2's just have a tuner turn them off.

 

Thank you for the reply, I don't have the code but the mechanic said it was the rear 02 sensors. If I have a tuner turn off the 02 sensors will it still pass state inspection? Will it still be okay to take on long trips?

 

Thank you for the reply, I'm not sure if it is the upstream sensors, the mechanic said it was the rear sensors if that helps. If I can find someone to tune it, tun them off will it still pass inspections? Will it still be okay to take on trips. I wish I knew more about cars, I always pay someone for maintenance.

 

Rear o2 sensors just monitor the cats alone.

As stated, when the cars are moved down line (IE High flow cats in the X pipe section), they are not as effect as the stock location cats, and the car starts to throw codes due to the new father away from the heads cats not being effecent as the the oem heads back at the head.

So turner tunes off all the rear SES reporting, so the car is not throwing codes. With the rear o2's not reporting codes, will pass inspection, and will be fine.

Here is a list of all the SES that need to uncheck, and change to no error reported.
https://www.corvetteforum.com/forums...and-430-a.html

 

You have an 05 C6. 05s used the E40 ECU. E40s process rear O2 sensors differently than the subsequent E38s and E67s. With an E40 ECU, the rear sensors are "tested" as being present upon a startup diagnostic built into the E40 that does not exist in E38s and E67s. This part of startup diagnostics cannot be turned off. The tuner can only shut off the periodic emissions check/reporting that all ECUs do.

The startup check the E40 does is nothing more than an electrical test that completes the circuit through the rear sensors. If the sensors are missing then an open circuit is reported as a fault. I haven't tuned an E40 in a while now, but the tune trick is to keep the O2 sensors plugged into their harnesses and just tiewrap them to a convenient place on the frame. This allows the ECU to complete its startup electrical test, then the periodic reporting is shut off by the tuner like any other rear sensor delete.

So, if you are finding that the harnesses for the rear sensors are just in place with no rear sensors then you need to add the rears so the E40 can complete startup diagnostics. Also, a little confused here BC you're saying the techs cannot figure out why the REAR sensors are not reporting? There is typically no place in LT headers for rear sensors. Make sure they're not confusing (you) talking rear sensors when they really mean front sensors moved back BC of the LTs.

One edit add: Dealer techs do not have access to the ECU programs and tables. That is only a function of third party SW like EF Live or HPT. Unless the tech is a tuner himself using one of these third party SW programs, the dealer tech is in a "dark place" regards fault codes that have been manipulated by a tuner. In other words, the dealer tech is not going to be able to reverse anything the tuners of the past have done to the ECU.