Knock Sensor 1, Checking

Knock Sensor 1, Checking

Observe all safety precautions: => [ Safety Precautions ] Generic Scan Tool

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

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) (J623) 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. Refer to => [ Preliminary Check ] Preliminary Check

Start diagnosis

- Remove the engine cover with air filter. Refer to appropriate service information.





• Before disconnecting the Knock Sensor electrical harness connectors, mark the component location.

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





Checking internal resistance

- Using a multimeter, check the Knock Sensor terminals 1 to 2 for an internal short.





Specified value: infinite (Infinity).

If the specified value was not obtained:

- Replace the faulty Knock Sensor (KS) 1 (G61). Refer to appropriate service information.

If the specified value was obtained:

Checking wiring

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

- Install the test box.

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

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service information.

- Using a multimeter, Check the Knock Sensor electrical harness connector to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 for an open circuit.





Specified value: 1.5 ohms Max.

If the specified value was not obtained:

- Check the wiring connection for an open circuit.

- Check the wiring connection 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 the faulty Knock Sensor (KS) 1 (G61). Refer to appropriate service information.

If no malfunction is found in the wiring and the resistance was OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service information.

- Install the engine cover with air filter. Refer to appropriate service information.

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.