The knock sensor is attached to the cylinder block and senses engine knocking. The sensor contains a piezoelectric element that converts vibration (or noise) into voltage signal and sends this signal to ECM. With input signals from camshaft position and crankshaft position sensor, ECM can identify which cylinder is knocking. ECM filters vibrations and determines if the vibrations are knocking signal. The Engine Control Module (ECM) uses this signal to suppress knocking by retarding ignition timing. The ECM will set a code (Malfunction Indicator Lamp will Not turn on) if during two driving cycles the Knock sensor’s output voltage falls below minimum threshold. This code indicates an unexpected vibration is being read by the Knock sensor or ECM under normal engine operation.
If the normalized reference signal exceeds the upper limit based on engine RPM , P0331 is set.
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal check Low
Poor connection
Open or short to ground in signal circuit
Short to power in signal circuit
Knock sensor
Enable Conditions
ECT > 40?(104?)
Engine speed > 2400rpm
Engine load > 35%
Threshold Value
Normalized reference level < lower limit, f(rpm)
ECT 40?(104?)
Engine speed > 1600rpm
Normalized reference level > upper limit, f(rpm)
Diagnostic Time
Continuous
MIL On Condition
2 Driving Cycles