Knock Sensor (KS) 1 G61 / Knock Sensor (KS) 2 G66 , checking

The following procedure is used to diagnose all Knock Sensors.

Special tools, testers and auxiliary items required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The mounting bolt of Knock Sensor (KS) 1 G61 / 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. Refer to → Motronic Engine Control Module (ECM) J220 , replacing 

Start diagnosis 

• Disconnect the green Knock Sensor (KS) 1 G61 electrical harness connector - 1  - or the gray Knock Sensor (KS) 2 G66 electrical harness connector - 2  -.

Checking internal resistance 

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

Specified value: ∞ (Infinity).

If the specified value was not obtained:

• Replace the faulty Knock Sensor (KS) 1 G61 / 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 Test Box 105 Pin VAG1598/31. Refer to 24 MULTIPORT FUEL INJECTION (MFI) for Engine Code AWD and 24 MULTIPORT FUEL INJECTION (MFI) for Engine Codes AWP and AWW .

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

• Remove the Motronic Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , replacing  .

• Using a Multimeter , Check the Knock Sensor electrical harness connector to the Motronic Engine Control Module (ECM) J220 electrical harness connector T121 for an open circuit.

Knock Sensor (KS) 1 G61 electrical harness connector terminals	Motronic Engine Control Module (ECM) electrical harness connector T121 terminals or test box sockets
1	106
2	99

Knock Sensor (KS) 2 G66 electrical harness connector terminals	Motronic Engine Control Module (ECM) electrical harness connector T121 terminals or test box sockets
1	107
2	99

Specified value: 1.5 Ω 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 wiring connection for damage, corrosion, lose 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 / Knock Sensor (KS) 2 G66.

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

• Erase the DTC memory. Refer to → Diagnostic Mode 04: Reset/delete diagnostic data 
• Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to →Readiness Code  .

• End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

• Replace the MFI Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , 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.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

• End of diagnosis.