Flat type knock sensors (non-resonant type) have structures that can detect vibrations over a wide band of frequencies: between approximately 6 kHz and 15 kHz.

Knock sensor is fitted onto the engine block to detect engine knocking.

The knock sensor contains a piezoelectric element which generates a voltage when it becomes deformed. The voltage is generated when the engine block vibrates due to knocking. Any occurrence of engine knocking can be suppressed by delaying the ignition timing.


DTC Detection Condition

Trouble Area


Output voltage of knock sensor less than 0.5 V (1 trip detection logic)

• Short in knock sensor circuit



Output voltage of knock sensor more than 4.5 V (1 trip detection logic)

• Open in knock sensor circuit

When any of DTCs P0327 and P0328 are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the ignition switch is turned off.

Reference: Inspection using an oscilloscope

1 V/ Division

1 ms./ Division

The correct waveform is as shown.





Equipment Settings

1 V/Division 1 ms./Division


Keep engine speed at 4,000 rpm with warm engine

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook

Post a comment