2003 Chevy 1500HD 6.0L---P1516

I have a 2003 Chevy 1500HD 6.0L 4x4. I’ve recently started getting the “Reduced Engine Power” light along with the P1516 Fault code. I’ve checked all the wires going to the TAC Module, TPS, and MAP, all appear to be in good condition. The Throttle Body is clean and the "flapper moves freely with no sticking. I only have this issue when it is warm outside. Recently we’ve had fairly code days between 32-50 degree weather but on the few days that it has gotten warmer, I’ve had the issue. Since it seems to only happen when its warm, I believe it to be a moisture issue, but I’m not sure. Any help would be greatly appreciated.

bad TP sensor is a very likely cause. If PCM doesn’t know where throttle is, it wont let you have any control of it

But it only happens when it’s warm outside. Wouldn’t it be always giving me issues if it was bad?

maybe, maybe not. Electronic parts are greatly effected by temperature, They are known to go bad on the 5.3 and 6.0 engines

google p1516 Chevy Silverado. You will be up reading all night


GM also had a problem with the throttle body pigtails on those 6.0 motors. The wires sometimes get brittle right close to the connector. The symptom is a reduced engine power light.

thanks for all of the help. from everything that I’ve read about it, is that it can be a number of things from as small as a loose wire or ground wire to having to replace the TAC module or the throttle body!