Possible causes

– Dirty Oil
– Engine mechanical problems
– Faulty camshaft position sensor
– Faulty crankshaft position sensor
– Timing belt jumped

Tech notes

There is a factory service bulletin for the following Hummer models:

2004-2009 Hummer H3
2004-2009 Hummer H3 Factory Service Bulletin OBDII Code P0017

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0017 HUMMER Description

The Camshaft Position (CMP) actuator system enables the Engine Control Module (ECM) to change the timing of the camshafts while the engine is operating. The CMP actuator solenoid signal from the ECM is pulse width modulated (PWM). The ECM control the CMP actuator solenoid duty cycle by controlling the amount of solenoid IN time. The CMP actuator solenoid controls the advance or retard of each camshaft. The CMP actuator solenoid control the oil flow that applies the pressure to advance or retard the camshafts.4
Ignition voltage is supplied directly to the CMP actuator solenoid. The ECM control the solenoid by grounding the control circuit with a solid state device called a driver. Th ECM compares the camshaft position or the camshaft angle, to the position of the crankshaft. If the ECM detects a deviation between the camshaft position target and the crankshaft position, the code will set.

HUMMER Technical Service Bulletins for P0017 code