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 PCM. With input signals from camshaft position and crankshaft position sensor, PCM can identify which cylinder is knocking. PCM filters vibrations and determines if the vibrations are knocking signal. The PCM uses this signal to suppress knocking by retarding ignition timing. The PCM 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 PCM under normal engine operation.
Checking the range of input signal with a knock sensor under detecting condition, PCM senses short in knock sensor circuit or malfunction of sensor. If the average value of the knock signals is out of the threshold value. during standard duration, PCM sets P0326. MIL(Malfunction Indicatin Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item
Detecting Condition
Possible cause
DTC Strategy
? Signal short
? Poor connection
? Short in harness
? Knock sensor
? PCM
Enable Conditions
? Pressure in intake manifold is normal.
? Engine speed =2000 rpm
Threshold value
? Knock Filtered Value < 5 or > 65
Diagnosis Time
? Continuous
MIL On Condition
? 2 driving cycles