Check Engine light!!!

[BtheBuck]

Vehicle: 2008 chevy Silverado z71

Hooked the code reader up to it and it is giving me PO121. I did my online research and have replaced the TPS, the Peddle position sensor, and cleaned the throttle body. I have cleared the codes each time by disconnecting the battery for 30 min. Once everything is up and running the light is coming on within 5 minutes of driving.

The truck runs great so no issues there. Any advice?

I need to fix ASAP. So if it is something that I need to take to a mechanic, I need an honest and affordable mechanic.

Once again, thanks in advance for the feedback.

[cpr1979]

Did it say what the code was for? My '08 did that and it was saying the fuel was too rich. I filled up with E85 and disconnected the negative cable for a few minutes. It went off and never came back on. Worth a try

[WCB]

Vehicle: 2008 chevy Silverado z71

Hooked the code reader up to it and it is giving me PO121. I did my online research and have replaced the TPS, the Peddle position sensor, and cleaned the throttle body. I have cleared the codes each time by disconnecting the battery for 30 min. Once everything is up and running the light is coming on within 5 minutes of driving.

The truck runs great so no issues there. Any advice?

I need to fix ASAP. So if it is something that I need to take to a mechanic, I need an honest and affordable mechanic.

Once again, thanks in advance for the feedback.

How did you clean the throttle body? Just spray into it or remove and clean? I had to take mine off and give it a squeaky clean cleaning.
But I'm not familiar with the chevy or that code...
There is a TBHer in your area that has a shop. Let me look for his name and I'll get back to you shortly. Just got to work and I supposed to be working OT right now so it might take me a few...

[WCB]

Just checked that code

Have you cleaned the electrical connections? Possible that they are dirty or electrolysis has set in and your getting a faulty voltage to the ECM. Or the ECM could be bad...

[BtheBuck]

How did you clean the throttle body? Just spray into it or remove and clean? I had to take mine off and give it a squeaky clean cleaning.
But I'm not familiar with the chevy or that code...
There is a TBHer in your area that has a shop. Let me look for his name and I'll get back to you shortly. Just got to work and I supposed to be working OT right now so it might take me a few...

I removed the throttle body and cleaned with a rag and engine cleaner. I couldn't get under the flaps real good cause I read if you move the flap much it can mess up the idle on the truck.

[quarterback]

Gas cap?

[sailor]

You dont mention mileage. Or what the code is.
Just speculation, but it could be bad O2 sensor,
or EGR valve.

[Harry]

When you clean throttle body us X66A ACDelco spray it's best for GMs, if you need any parts I work for XLparts and we are ACDelco vendor

[miket]

I removed the throttle body and cleaned with a rag and engine cleaner. I couldn't get under the flaps real good cause I read if you move the flap much it can mess up the idle on the truck.

Yep, moving it will make it go crazy. The TPS on my wifes 2008 Tahoe did the same thing, got the same code. Cleaning didnt help. I replaced it. Supposedly there is a sequence of starting, idling etc that is supposed to make the computer learn the new throttle body but it didnt work on ours. I had to take it to the dealer for a throttle position relearn. I think it was $90 or so. The throttle body was like $250 I think. Easy to replace.


On edit: yours may be different than mine, the TPS was all one unit with the throttle body.......

[WCB]

Contact BIGTERRY75 on here. He has a shop in Rockwall.

Owner: Southwest Car Care

972 seven seven 1 5 4 88

[AntlerCollector]

I put a small strip of electrical tape over my check engine light. I havnt seen it come on since.

[WCB]

You dont mention mileage. Or what the code is.
Just speculation, but it could be bad O2 sensor,
or EGR valve.

PO121 according to the first post

[Big Lee]

Go to the throttle body connector. Pull back the plastic overlay insulation 8-10inches. Trace each strand back. If you feel an imperfection in the wire or notice a size difference there could possibly be a break. The brown or yellow wire pay close attention to. I've had several instances with them breaking.

[BtheBuck]

Go to the throttle body connector. Pull back the plastic overlay insulation 8-10inches. Trace each strand back. If you feel an imperfection in the wire or notice a size difference there could possibly be a break. The brown or yellow wire pay close attention to. I've had several instances with them breaking.

This is my plan for this morning, we will see what happens.....after that I am not sure, may be taking it in somewhere. Truck is solid, but as stated, I just need that light off.

All, thanks again for the input, I will update on my findings.

[texashunter08]

I just had the same problem with my chevy i pulled the throttle body and cleaned even move the flap to clean the seat. Put it back on and pulled the battery cable off for 30 mins and it cleared then it came back on. So i pulled the battery cable off again and it reset and still hasn't come back on. When you move the flap on the Throttle body it will cause it to idle high but should clear up in about 200 miles or so