Knock Sensor: Inspection

Standard resistance: 

120 to 280 kΩ at 20°C (68°F) 

If the result is not as specified, replace the knock sensor.

• A flat type knock sensor (non-resonant type) has a structure that can detect vibrations between approximately 6 kHz and 15 kHz.
• Knock sensors are 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.
  Fig 1: Measuring Resistance Of Sensor

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE
  
  

  DTC No.	DTC Detection Condition	Trouble Area
  P0327	Output voltage of knock sensor is 0.5 V or less (1 trip detection logic)	Short in knock sensor circuit Knock sensor ECM
  P0328	Output voltage of knock sensor is 4.5 V or more (1 trip detection logic)	Open in knock sensor circuit Knock sensor ECM

HINT:

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

Reference: Inspection using an oscilloscope. The correct waveform is shown.

Fig 2: Waveform Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002