P0333 indicates the Powertrain Control Module (PCM) is receiving an abnormally high voltage signal from the knock sensor (often knock sensor 2 or the sensor on bank 2 in V-engines). Knock sensors detect abnormal engine vibrations caused by detonation/knocking. A circuit high condition typically means the sensor or its wiring is shorted to a higher voltage source, or the sensor has failed in a way that produces excessive output.
The knock sensor internal element has failed, producing an artificially high voltage signal that the PCM interprets as a fault.
The knock sensor signal wire has insulation damage and is shorted to a higher-voltage circuit (such as battery power, ignition switched power, or other sensors).
The sensor connector pins are corroded, bent, or contaminated, creating an abnormal resistance path or short condition.
The harness running to the knock sensor has been damaged by heat, abrasion, or rodents, causing a direct short or intermittent connection.
Improperly installed accessories (alarm, stereo, remote start) have tapped into or damaged the knock sensor circuit.
The PCM input circuit for the knock sensor has failed. This is extremely rare compared to sensor and wiring faults and should be diagnosed only after all other causes are ruled out.
Yes, you can typically drive short distances, but the engine may run with reduced timing advance because the PCM cannot rely on knock sensor input for detonation protection. Prolonged driving with undetected knock can damage engine components over time.
Knock sensor prices vary significantly by vehicle make and model. The sensor itself is relatively inexpensive, but labor costs depend on its location - some are easily accessible while others require significant disassembly.
In some cases, a technician may suspect the PCM after ruling out the sensor and wiring, but this is very rare. P0333 is an input circuit code - the sensor and wiring are the source in the overwhelming majority of cases. Always verify sensor and wiring thoroughly before considering PCM replacement.
A failed knock sensor prevents the PCM from detecting detonation, so the engine may run with excessive timing advance in certain conditions. This can lead to engine pinging and potentially cause damage to pistons, spark plugs, or connecting rods over time if not repaired.