SES Light, Engine Misfire and Valvetrain Tick Noise - Inspect Valve Springs - keywords CEL crack DTC engine light MIL miss P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 rattle rough valvetrain

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

On rare occasions, a SES Light, engine misfire, and valvetrain tick noise may be experienced. Upon inspection, a P0300 - P0308 DTC may be stored. This may be the result of a broken valve spring.

Complete the current SI diagnostics for any symptoms or DTCs found

If diagnostics are inconclusive, or diagnostics led to a internal engine valve train concern, inspect for a broken valve spring. If a broken valve spring has been verified, inspect the intake manifold runner for damage. The intake manifold runner on the effected cylinder may be deformed by excessive cylinder temperatures. During repairs make sure that the pushrods are not bent, and there is no damage to any other valve train components.

If a broken valve spring has been verified, check the build date of the vehicle. If the vehicle was built prior to September 16th, 2005 all 16 valve springs need to be replaced. Replace the valve springs with the existing part numbers found in the GMSPO catalog.

If the vehicle is built after September 16th, 2005 replace only the broken valve spring.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.