Knock Sensor, Checking

Knock Sensor, Checking

The following procedure is used to check Knock Sensor (KS) 1 (G61) and Knock Sensor (KS) 2 (G66).

• 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 Engine Control Module (ECM) (J623) fuses OK.

• Battery voltage at least 12.5 V.

• 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 customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.

• The knock sensor electrical connectors can be identified by color. Knock Sensor (KS) 1 (-G61-) (Bank 1) is green. Knock Sensor (KS) 2 (-G66-) (Bank 2) is gray.





- Disconnect the electrical harness connector - 1 - or - 2 - of the respective knock sensor.

1 Knock Sensor (KS) 1 (-G61-.)
2 Knock sensor (KS) 2 (-G66-.)

Checking internal resistance

- Using a Multimeter , check as follows:





- Using a Multimeter, check the Knock Sensor (KS) 1 (G61)

- or Knock Sensor (KS) 2 (G66) terminals 1 to 2, 2 to 3, and 1 to 3 for an internal short.





Specified value: infinite (Infinity).

If the specified value was not obtained:

- Replace Knock Sensor (KS) 1 (G61) or Knock Sensor (KS) 2 (G66) as necessary.

If the specified value was obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box (VAG1598/42).

If the manufacturers test box is not being used, perform the following step.

- Remove the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter , check the knock sensor electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector for resistance.

• Knock Sensor (KS) 1 (-G61-)





• Knock Sensor (KS) 2 (-G66-)





Specified value: 1.5 ohms max.

If the specified value was not obtained:

- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

- If necessary, repair the 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. Refer to => [ Diagnostic Mode 04 - Erase 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. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:

- Replace the Engine Control Module (ECM) (J623). Refer to=> [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- 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. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

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

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