Knock Sensor 1

The following procedure is used to diagnose Knock Sensor (KS) 1 -G61- which is controlled by Motronic Engine Control Module (ECM) - J623-.

Special tools and workshop equipment 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.

Procedure 

-- Remove the front engine cover -1-.

-- Disconnect the orange Knock Sensor (KS) 1 -G61- electrical harness connector -9-.

Checking internal resistance

-- Using aMultimeter, 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-. Refer to Component Locations Overview .

If the specified value was obtained:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

-- Install the test box. Refer to Wiring and Components, Checking with Test Box VAG 1598/42 .

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

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REMOVING AND INSTALLING .

-- Using a Multimeter, check the Knock Sensor (KS) 1 -G61- electrical harness connector to the Motronic Engine Control Module (ECM)J623 electrical harness connector T60a for an open circuit.

Knock Sensor (KS) 1 -G61- electrical harness connector terminals	Motronic Engine Control Module (ECM)J623 electrical harness connector T60a terminals or test box sockets
1	39
2	54
3	52 (Shield)

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 Knock Sensor (KS) 1 -G61-. Refer to Component Locations Overview .

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

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REMOVING AND INSTALLING .

Assembly is performed in the reverse order of removal.

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.