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 number of knock sensor errors is over 25 times, PCM sets P0326.
Item
Detecting Condition
Possible Cause
DTC Strategy
Rationality check
Poor connection
Open or short in signal circuit
Knock sensor
PCM
Enable Conditions
Coolant temperature > 40?
Engine speed > 1520rpm
Threshold Value
Number of knock sensor errors > 25
Diagnostic Time
Continuous
MIL ON Condition
NO
Specification
Capacitance
950 ~ 1,350 pF