P0651 Chevrolet - 2500hd

Question

This code on 2008 Chevy 2500hd the gas ukr on the dash board screen says engine reduced power

Answer 1

P0651 could be related to 3 things, the throttle body, the accelerator pedal or the crankshaft position sensor 

I would start by cleaning the throttle body and doing idle air relearn (see steps below)