Greetings, I have a 2008 HHR with 2.2 non-vvt. It has fault P0016. Shop said it needed a timing chain. A timing chain kit was installed and still had fault code. Then the camshaft was replaced, still has fault. The cam and crank sensors replaced. Still has faults. Cam timing has been rechecked and verified correct. Anybody have any suggestions to what problem may be.