Knock Sensor, Checking

Knock Sensor, Checking

Knock Sensor 1, Checking

NOTE: Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the Knock Sensor (KS) 1 G61.

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements
- The mounting bolt of Knock Sensor (KS) 1 G61 tightened to 20 Nm.
- The Motronic Engine Control Module (ECM) J220 fuses OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.

Test procedure
- Perform a preliminary check to verify the customers complaint. General Diagnosis

Start diagnosis







- Disconnect the Knock Sensor (KS) 1 G61 electrical harness connector - 2 -.

Checking internal resistance







- Using a Multimeter, check the Knock Sensor (KS) 1 G61 terminals 1 to 2 for an internal short.

Specified value: (Infinity).

If the specified value was not obtained:
- Replace Knock Sensor (KS) 1 G61.

If the specified value was obtained:

Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box VAG1598/31.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a Multimeter, Check the Knock Sensor (KS) 1 G61 electrical harness connector to the Motronic Engine Control Module (ECM) J220 electrical harness connector for resistance.

Knock Sensor (KS) 1 G61 Motronic Engine Control Module (ECM)
electrical harness connector J220 electrical harness connector
terminals terminals or test box sockets
1 106
2 99
3 108

Specified value: 1.5 Ohms Max.

If the specified value was not obtained:
- Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and the resistance was not OK:
- Replace Knock Sensor (KS) 1 G61.
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Readiness Code
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) J220.
- Assembly is performed in the reverse of the removal.

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

End of diagnosis

Knock Sensor 2, Checking

NOTE: Use only gold-plated terminals when servicing terminals in the electrical harness connectors of the Knock Sensor (KS) 2 G66.

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements
- The mounting bolt of Knock Sensor (KS) 2 G66 tightened to 20 Nm.
- The Motronic Engine Control Module (ECM) J220 fuses OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.

Test procedure
- Perform a preliminary check to verify the customers complaint. General Diagnosis

Start diagnosis







- Disconnect the Knock Sensor (KS) 2 G66 electrical harness connector - arrow -.

Checking internal resistance







- Using a Multimeter, check the Knock Sensor (KS) 2 G66 terminals 1 to 2 for an internal short.

Specified value: (Infinity).

If the specified value was not obtained:
- Replace the Knock Sensor (KS) 2 G66.

If the specified value was obtained:

Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box VAG1598/31.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a Multimeter, Check the Knock Sensor (KS) 2 G66 electrical harness connector to the Motronic Engine Control Module (ECM) J220 electrical harness connector for resistance.

Knock Sensor (KS) 2 G66 Motronic Engine Control Module (ECM)
electrical harness connector J220 electrical harness connector
terminals terminals or test box sockets
1 107
2 99
3 108

Specified value: 1.5 Ohms Max.

If the specified value was not obtained:
- Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and the resistance was not OK:
- Replace Knock Sensor (KS) 2 G66.
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Readiness Code
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) J220.
- Assembly is performed in the reverse of the removal.

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

End of diagnosis