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 Engine Control Module (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.
The PCM monitors the range of the analog input signal from knock sensor to check sensor failure that is short circuit or open circuit. If the difference between knock signal and noise level is smaller than the threshold during defined time period, the DTC P0326 is set. P0326 will also set if the nose value exceeds the minimum or maximum thresholds.
Item
Detecting Condition
Possible Cause
DTC Strategy
Plausibility check
Open/short in signal or ground circuit
Poor connection or damaged harness
Faulty knock sensor
Enable Conditions
Knock detection function active
Engine rpm >2700 rpm
Air mass >0.5g/rev(250mg/tdc.)
No relevant failure
Threshold Value
Difference between the processed knock sensor signal and its mean does not exceed a threshold(0.08V) & the integral of the processed knock sensor signal does not reach the threshold(3V) for cylinders 2 and 3
If the mean processed knock sensor signal of any one cylinder leaves the valid range(0.1V~4.5V).
Diagnostic Time
100 rev.
Mil On Condition
Two trips