General Precautions of EFI System Maintenance
F-49
62. P0327 Circuit Voltage of Knock Sensor Signal Too low
Description about Malfunction Cause:
The knock sensor is installed on the engine body. The engine vibrates in different frequency of vibration
under different operating conditions, and generates voltage signals containing various frequencies. The
voltage signal may not only reflect whether or not the engine has experienced knock but also reflect the
background noise value of the engine (the noise of mechanical parts). When the engine is operating normally
and the knock sensor is working normally, the background noise value will fluctuate within the specified
range. Once the background noise value is lower than the set threshold, the system then believes that
malfunction exists in the signal circuit of the knock sensor.
Schematic Diagram:
Malfunction Diagnostic Guide:
Required Equipment: (Diagnostic Instrument with EOBD Diagnostic Function)
Step I: Use diagnostic instrument to read the malfunction information
Read Result I Read Result II
MIL Lamp On P-CODE Present MIL Lamp Off P-CODE Present
P0327
P0327
Maintenance tips:
The malfunction has been confirmed, and the
following problems may possibly exist
1) The circuit for the Pin 19# of ECU connected to
the Pin 1# of knock sensor in open circuit
2) The circuit for the Pin 20# of ECU connected to
the Pin 2# of knock sensor in open circuit
3) The circuit for the Pin 19# of ECU short to
ground
4) The circuit for the Pin 20# of ECU short to
ground
Maintenance tips:
The malfunction has not been finally confirmed, and
examine the following items:
1) Inspect the electric resistance of the circuit for
the Pin 19# of ECU connected to the Pin 1# of
knock sensor.
2) Inspect the electric resistance of the circuit for
the Pin 20# of ECU connected to the Pin 2# of
knock sensor.
3) Inspect the electric resistance for the Pin 19# of
ECU to ground.
4) Inspect the electric resistance for the Pin 20# of
ECU to ground.
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