just wondering if someone could tell me where to start on this. i have 4 codes and perhaps they are related to each other and could have one common problem, i dont know.
P0455 evap emission control leak
P0128 coolant temperature (ECT) below thermostat regulating temperature
P0606 PCM processor fault
P0014 camshaft position timing over advanced (bank 1)
this is on a 2004 envoy XL with about 85000 miles.
i just wondered where i should start? i was thinking of replacing the thermostat first. then maybe checking vacuum lines with some starting fluid. maybe replace the cam positioning sensor?