Knock Sensor, Checking

The following procedure is used to diagnose Knock Sensor (KS) 1 -G61- / Knock Sensor (KS) 2 -G66-.

Special tools and workshop equipment 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 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

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 105 Pin -VAG1598/31-.

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 J623, REPLACING .

-- Using a Multimeter, Check the Knock Sensor -- electrical harness connector to the Engine Control Module (ECM) -J623- electrical harness connector T121 for an open circuit.

Knock Sensor (KS) 1 -G61- electrical harness connector terminals	Engine Control Module (ECM) electrical harness connector T121 terminals or test box sockets
1	106
2	99
3	108

Knock Sensor (KS) 2 -G66- electrical harness connector terminals	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:

-- Replace the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE J623, REPLACING .

Final procedures 

After 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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .

End of diagnosis