This bulletin applies to 2009-2010 Chevy HHR models. In rare instances, a sharp, short rattle noise may be heard from the front of the engine at start-up. DTC P0011, P0014, P0016 or P0017 may also set during this condition.
If the noise is present and is very short and sharp in duration (two to five seconds), this may be an issue with the cam actuators not parking properly. Once the noise is verified as the actuators, they must be replaced. If the cam actuators are replaced, remove the CMP actuator solenoids to inspect for debris. If debris is found, clean and inspect for torn or loose screws and replace the solenoid if necessary.
If debris is found in the solenoids and actuators, be sure to change the engine oil and filter before returning the vehicle to service. In some cases it may be necessary to perform multiple oil and filter changes, with a test drive in between changes.