Knock Sensor (KS) , Checking

WARNING: This page is about a different car, the 2009 Audi A4, 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

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

Special tools, testers and auxiliary items required

Multimeter.
Wiring diagram.

NOTE:

Cylinders 1, 2, and 3 (bank 1) are monitored by Knock sensor (KS) 1 -G61-. Cylinders 4, 5, and 6 (bank 2) are monitored by Knock sensor (KS) 2 -G66-.
Knock sensors themselves cannot be checked electrically.
When servicing terminals in the harness connector of knock sensors, use only gold-plated terminals.
For the knock sensors to function properly, it is important that the tightening torque be exactly 20 Nm.
Contact surfaces between Knock Sensor (KS) 1 G61 and Knock Sensor (KS) 2 G66 and cylinder block must be free of corrosion, dirt and grease.

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 → General Diagnosis .

Start diagnosis

Fig 1: Removing/Installing Rear Engine Cover

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove the rear engine cover - arrows -.

Checking knock sensor and wiring

NOTE:

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.

Fig 2: Disconnecting Electrical Harness Connectors

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Fig 3: Identifying Knock Sensor Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Using a Multimeter , check the Knock Sensor terminals for an internal short.

Knock Sensor (KS) Electrical harness connector terminals
1 + 2
1 + 3
2 + 3

Specified value: ∞ (Infinity).

If the specified values are not obtained:

Replace the faulty Knock Sensor (KS). Refer to → 15 - ENGINE - CYLINDER HEAD, VALVETRAIN .

If the specified values are obtained:

Checking wiring

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

Install the test box. Refer to → 24 - FUEL INJECTION SYSTEM .

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 (ECM) J623 , Removing and Installing .

Fig 4: Identifying 3-Pin Connector Terminals 1 & 3

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Knock Sensor (KS) 1 G61 electrical harness connector terminals	Engine Control Module (ECM) electrical harness connector T60 terminals or test box sockets
1	41
2	58
3	42

Knock Sensor (KS) 2 G66 electrical harness connector terminals	Engine Control Module (ECM) electrical harness connector T60 terminals or test box sockets
1	56
2	57
3	42

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). Refer to → 15 - ENGINE - CYLINDER HEAD, VALVETRAIN .

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 (ECM) J623 , Removing and Installing .

Assembly is performed in the reverse order of removal, note the following:

Final procedures

After repair work, the following work steps must be performed in the mentioned sequence:

Check the DTC memory.
If necessary, erase the DTC memory. Refer to Diagnostic Mode 04: Reset/delete Diagnostic Data .
If the DTC memory was erased, generate readiness code. Refer to Readiness Code .

End diagnosis and switch ignition off.