I bought a used 2012 Chevy Silverado 4 months ago, great condition. Currently has 45,000 miles.

Anyway, I was driving up the highway last night and my truck started to jump/shut off at the same time. I got the error code on my dash that says "reduced engine power" or something like that. I came to a stop and turned the truck off. Upon turning it back on, the check engine light was on, but it seemed to drive okay. I managed to drive to the nearest AutoZone to get a diagnostic test, which gave me the error P2135. I learn it has something to do with the throttle body and sensors. I park my truck overnight at a local establishment and plan to pick it up in the morning to take it to a mechanic.

This morning I go to pick my truck up from the parking lot I left it at. When I turn it on, check engine light is off and I proceed to drive it to a mechanic. The truck drove normal to the mechanic. Told the mechanic what happened to me and they said they would take a look at it. He said he would call when he has news...

I get the call, he asked me if any work has been done to the throttle body. He says he asks because it looked very clean and almost new. I am not aware of any work done to the throttle body, unless it was done privately by a previous owner. The mechanic said they updated the software system, he took it for a test drive and no problem.

I hope an update to the system works. However, I hear P2135 is a common problem with the 2nd gen Silverado's... and I read of so many posts of how this problem drags on for a long time. I have read of many different problems with P2135, and each one is different. It might go off now, but could happen again to me in 200 miles. I'm just not convinced a software update is going to fix my problem (according to what I have read)...

Any suggestions on what I should do? What to expect? How do I go about this?

Thanks!

 

The TB has 2 position sensors in it - sensor A and sensor B. They must remain within a specific range of voltage to one another (they have to “agree”) in order for the throttle actuator system (meaning the throttle body and accelerator pedal) to function properly. P2135 indicates that range has been exceeded for more than about 2 seconds. Any problem with the TAC will default the engine into reduced power.

I can’t recall what the readings are supposed to be at the moment - some of them start both sensors at about 0.5 volts closed throttle and the readings should shadow each other as the throttle is opened; and some of them start one sensor at 0.5 volts and the other at 4.5 volts closed throttle with the signals intersecting at a certain point.

In my experience the most common causes of this code are loose terminal connections at the throttle body and the accelerator pedal, loose/corroded grounds at the ends of the cylinder heads, and damage to the wiring harness. I’d recommend starting with inspection of the harness and connections - if there is a problem you might be able to trigger reduced engine power by wiggle testing the harness with the engine running.

The signal circuits can be monitored by back probing at pin D (dark green) and pin F (purple) at the throttle body connector with a multimeter. Pin E (gray) is the 5 volt reference from the PCM.

 

Thank you, sir. I appreciate the response! I will keep all this info and play around with it