I have a 2007 HHR with 136500 miles. Got my first reduced message and the engine light came on. Took it to Autozone to have it "read" and got the following message:
Troubleshooting P1516
Definition:
TAC module throttle actuator position performance
Explanation
the ECM has detected an out of range condition between the predicted and actual throttle position
Probable cause
Poor connection at the TAC module
Failed TAC module
Check TPP or TPS sensors
Binding or bent throttle plate failed throttle body

Then I took it to a service station to discover once they checked it out, it would cost 462.00 to fix it. My "baby" will be parked for a while Sigh

 

1. Get a second opinion.

2. Find a person that owns a socket set to R&R the throttle body. It is only a few bolts, no magic involved.

Source a new or used throttle body. For a new one give www.GMpartsoutlet.net a try, or any of the online GM parts stores, or EBay. For used any salvage yard.

 

Possible causes
- Faulty Throttle Actuator Control (TAC) module
- Throttle Actuator Control (TAC) module harness is open or shorted
- Throttle Actuator Control (TAC) module circuit poor electrical connection
- Check Throttle Actuator Control (TAC) module connector for water
- Binding or bent throttle plate-failed throttle body

Read more: http://engine-codes.com/p1516_chevro...#ixzz2rN3NaFvd

 

Welcome to the site here is a youtube video about code p1516 that helps explain about the throttle body. The video is not an hhr but the system is the same.

 

Future son in law and my husband read through the posts and watched the video. Thanks Lucky and donbrew for your insite!! The throttle body had some dampness on it/in it they found when they took it off. They cleaned it up and put it back on and, TA DA! so far so good! THANK YOU so much!!

 

A glad your running again hopefully that will take care of the problem.

Keep us posted.

 

and to the forum!