2012 Porsche Cayenne S Hybrid – Startup Rattle and P0021
- Aug 16
- 1 min read
CUSTOMER CONCERN
The engine rattles during startup, misfires on all three bank-2 cylinders, and stores DTC P0021.
CAUSE
Camshaft timing was incorrect from a failed timing chain; a supporting confirmed report also documents worn guides and a camshaft actuator.
CORRECTION
Remove and replace the failed timing chain and related worn timing components, set camshaft timing to specification, clear DTC P0021 and the bank-2 misfire faults, and verify quiet startup and correct engine operation.