Knock Sensors, Checking

Diagnostic Procedures

Knock Sensors, Checking

• Contact surfaces between knock sensor and cylinder block must be free of corrosion, dirt and grease.

• For the Knock Sensors to function properly, it is important for tightening torque to be exactly 20 Nm.

• Use only gold-plated terminals when servicing terminals in harness connector of knock sensors.

Special tools, testers and auxiliary items required

• Multimeter (VAG1526) or Multimeter (VAG1715)

• Connector test kit (VAG1594)

• Wiring diagram

Test requirements

• Mounting bolts of knock sensors tightened to 20 Nm.

• Ignition switched off.

Test sequence

Knock Sensor (KS) 1 (G61)

- Disconnect black 3-pin harness connector for knock sensor 1 (arrow).





Knock Sensor (KS) 2 (G66)

- Disconnect black 2-pin harness connector for knock sensor 2 (arrow).





Checking wires to Engine Control Module (ECM)

- Connect test box to control module wiring harness , connect test box for wiring test.

Knock Sensor (KS) 1 (G61)

- Check wires between test box and 3-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.





Wire resistance: max. 1.5 ohms





- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: infinite ohms

If no malfunctions are found in wires:

- Replace Knock Sensor (KS) 1 (G61).

- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code.

Knock Sensor (KS) 2 (G66)

- Check wires between test box and 2-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.





Wire resistance: max. 1.5 ohms





- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: infinite ohms

If no malfunctions are found in wires:

- Replace Knock Sensor (KS) 2 (G66).

Final Procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to --> [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to --> [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to --> [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.