DTCs P1128 and P1129

[NoMatter]

Sounds like a tough one to troubleshoot. Did the thermostat do the trick?

[Matt]

Nope... damn codes popped back on today.

I removed the Superchips tune. Going to run it stock for a while to make sure the codes come on with the stock programming. Next thing im going to do is try timing the 02 sensors to see how long they take to heat up; if they're close to the 40 second limit then i may try replacing them ($30/each isn't bad). If that's not it, I may be using my certified preowned warranty and letting my dealer take a look in case its the PCM.

[The_War_Wagon]

Nope... damn codes popped back on today.

I removed the Superchips tune. Going to run it stock for a while to make sure the codes come on with the stock programming. Next thing im going to do is try timing the 02 sensors to see how long they take to heat up; if they're close to the 40 second limit then i may try replacing them ($30/each isn't bad). If that's not it, I may be using my certified preowned warranty and letting my dealer take a look in case its the PCM.

So what finally happened?

[Matt]

02 sensors timed out OK.

Put the stock tune back in and just adjusted for tire size and haven't had the codes come back... yet...