Knock sensors are used to detect engine detonation. The ECM will retard the spark timing based on signals from the knock sensor module. The knock sensors produce an AC voltage signal that is proportional to the amount of vibration the engine is experiencing. The ECM records a fault when the engine noise exceeds a certain threshold (based on engine load and speed). After 20 faults have been recorded, this code will set.

DTC P0333 will set if there is a fault in knock sensor system and the following conditions are met:

P0333 is a (type C) DTC.

To locate an intermittent problem use the scan tool to monitor knock sensor 2 voltage with engine running.

Wiggling wires while monitoring knock sensor 2 voltage may locate area where a short to voltage may exist.

Possible Causes:

The ECM has the ability to learn spark retard. If knock is present long enough a reduced power condition may result due to max spark retard. Spark will eventually be returned to normal when knock condition is corrected.