Knock Sensor: Testing and Inspection

CHECKING KNOCK SENSORS

NOTES:
^ Also Refer to On-Board Diagnostics, "Read Measuring Value Block" function 08, display group 015 and/or 016 for functional testing of the knock sensor.
^ Remove and install with insert 3247.
^ Exact compliance with the tightening torque of 20 Nm (15 ft lb) is critical for satisfactory function of the knock sensors.
^ Check harness connection for corrosion.
^ Use only gold terminals to repair knock sensor harness connectors.

CHECKING KNOCK SENSOR WIRING

3-Pin Connector:

- Separate knock sensor harness connectors in engine compartment.
- Check all three terminals at each knock sensor connector for short circuit to each other.

If a connection exists:
- Replace knock sensor.

CHECKING WIRING FROM KNOCK SENSORS TO ECM
- Connect VAG 1598/19 test box to ECM wiring harness. Refer to Computer and Control Systems, System Diagnosis, VAG 1598 Pin Out Box Connecting.
- Check wiring between sensor and ECM for open circuit or short circuit using wiring diagram.

3-Pin Connector:

Terminal assignment of connector:
1 - Ground
2 - Signal wire
3 - Shield

- Check knock sensor 1 -G61- signal wire for continuity between terminal 2 of connector in engine compartment and test box socket A 13.
^ Specified value: maximum 1.0 ohm
- Check knock sensor 1 -G61- Ground wire for continuity between terminal 1 of connector in engine compartment and test box socket A 14.
^ Specified value: maximum 1.0 ohm
- Check knock sensor 1 -G61- shielding for continuity between terminal 3 of connector in engine compartment and engine ground.
^ Specified value: maximum 1.0 ohm
- Check knock sensor 2 -G66- signal wire for continuity between terminal 2 of connector in engine compartment and test box socket A 15.
^ Specified value: maximum 1.0 ohm
- Check knock sensor 2 -G66- Ground wire for continuity between terminal 1 of connector in engine compartment and test box socket A 14.
^ Specified value: maximum 1.0 ohm
- Check knock sensor 2 -G66- shielding for continuity between terminal 3 of connector in engine compartment and engine ground.
^ Specified value: maximum 1.0 ohm

If specified values are not obtained:

- Repair break in wiring and/or short circuit between sensor connector and ECM connector.

KNOCK SENSOR 1 (Right Cyl. Bank):
Blue sensor ECM connector
connector terminal terminal
1 (Ground) A 14
2 (Signal) A 13
3 (Shield) Ground

KNOCK SENSOR 2 (Left Cyl. Bank):
Green sensor ECM connector B
connector terminal terminal
1 (Ground) A 14
2 (Signal) A 15
3 (Shield) Ground