P0331

DIAGNOSTIC TROUBLE CODE P0331
Front knock sensor (cylinders 2-4-6), control module input absent/no continuity or short circuit

Fault Symptom.
Engine performance may be down, continuous retardation of the ignition timing.

Condition
In the case of a short circuit or open circuit, a diagnostic trouble code will be generated it engine rpm exceeds 2000 rpm and the coolant temperature is above 45°C (113°F).

Diagnostic Procedure.
1. Connect the Scan Tool.
Start the engine and warm it up.
Rev up the engine vigorously.
Select "READ FUNCTIONS",
Select "KNOCK CONTROL".
This command shows the current retardation of the ignition timing.
On opening the throttle the Scan Tool display should change from "0 DEGREES" to "12 DEGREES".
This is the maximum ignition timing retardation, safety retard, to prevent knocking.

If the Scan Tool shows an ignition retard of "12 DEGREES", continue with step 2.
If the Scan Tool shows a different ignition retard, proceed to step 3.





2. Check the electrical interface in the knock sensor connector.
Unplug the 2-pin connector.
Ignition switch in the OFF position.
Take the following readings on the female connector:
- Voltage across pin 2 and battery positive____ about 12 V.
- Check the connector for corrosion.
- Resistance across pins 1 and 2 about 1 Mohm.

If the voltage reading is not OK, check the screened lead between pin 2 and crimped connection J127 for continuity.
If the resistance reading is not OK, check the lead between pin 29 of the control module and pin 1 for continuity or a short circuit.
If the readings are OK, continue with step 3.





3. Check that the knock sensor is tightened to a torque of 22 Nm (16 ft lb) and then check the knock sensor signal by measuring the voltage directly on the sensor connector while lightly tapping the sensor retaining screw.
- The voltage should then go up to at least 100 mV AC.
The knock sensor for the front cylinder bank is easily accessible.
The knock sensor for the rear cylinder bank is Not easily accessible.
Furthermore, there is a danger of shorting to the starter motor.

CAUTION: If in any doubt it is advisable not to carry out this operation.

If no voltage reading is obtained (the knock sensor seems to be completely "dead"), fit a new sensor.

4. Clear the diagnostic trouble code and drive the car to see whether the DTC is generated again.

If the diagnostic trouble code is generated again, continue at "Procedure Before ECM Replacement". Component Tests
If the trouble code is not generated again the remedial measure taken was correct, otherwise the fault is of intermittent type.