Driving to work this morning just cruising at 35mph and then I hear chimes and see the Engine Power Reduced across the DIC.

Scanned tonight and got..

P2135 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation

P1681 Control Module Throttle Position (TP) System Performance

 

I had to take my car to the dealership 3 times before they fixed it with similar issues. I had P2135, P2138, P1516, and 2 or 3 other codes as well. To make a long story short, they wound up finally replacing the computer and that was the problem.

https://www.cobaltss.net/forums/prob...-p0121-256367/

This thread was not started by me, but I was putting my updates up as the dealer kept screwing up and not finding the problem. If you want to read, feel free.

 

Yes! I did read that. See though everyone seems to get like 6+ codes.. I only got these 2.

My PCM does not fall under the "replacement" for the build date either..

 

After I did an m62 swap, after a super heavy rain I would get a P2119 throttle closed position performance; Shortly thereafter I got the P2135 TP sensor 1-2 correlation...
After looking at some posts here and talking to some of the other techs at work, I decided to just throw a new TB on it. I have about 6-7K miles on the new throttle body and so far so good.
I dont know much about the 1681 code; but i will look at the solus tomorrow at work and look at mitchell also and report back...

But my current diagnosis is TB.


by the way, Have you ever cleaned your throttle body?

 

Right, I've heard this problem occurs when it rains. No rain here in the past week, so I think that is ruled out. Car is garage kept anyhow.

TB is cleaned every oil change. If not every oil change, (sometimes I just don't have the time), then every other oil change for sure.

TB is clean, connector is nice and secure. No visual open wires. Everything is nicely packed in the loom(s). The wiring in this car is actually really organized and protected.. Some people say they have wires out of looms and ****.. Not the case with my cobalt. I looked for open wires for ***** and giggles though and everything is in order.

Let me know! Thanks!

Once again just for reference - My PCM is out of the Julian build date where the PCM needed to be replaced.

Lastly - Does the TB make any funny noises or anything? Mine is quiet as a mouse. No funny noises I've ever noticed.. Not even to this day.

 

My PCM did not fall under the "repacement" for the julian date either, but that was still the problem.

I have read on here that a new throttle body fixes most codes dealing with the TB though. I replaced the TB 2 times with "new" used ones, both times it "fixed" my car for a about 2 months. The next time no matter what I did, I could not make it run right agian, (another new TB, cleaned the old one and put it back on, replaced the gas pedal twice, cleaned all connectors, put dielectric grease on the connectors, checked all the wiring I possibly could have, etc...) so I brought it to the dealer and the computer was ultimately the problem for me.

 

Did your car ever have cold idle problems before you had the codes and the engine power reduced message?

Seems my car has been idling like complete ass for a few months when the car is cold.. For probably 5 minutes after being started.

A guy on here said his did the same thing then his TB finally took a ****. Which would make sense. P2135 is a code used for EITHER the pedal sensor OR the TB. As far as I know anyhow.

It's the P1681 code which makes me nervous.

 

The 1681 is likely to be a throttle body.

The 2135 is a bit more difficult to narrow down without doing some in-depth tests. I've seen a common thread on Ions though where replacing the APP connector and running all new wires from the APP to the ECM under the hood will cure the issue.

 

No, I never had a cold idle problem, I had to replace the evap purge solenoid once, but that was the only issue I ever had with my car until this happened. When I would get the codes though, I would get this real rough idle that would make the entire car shake.