Knock Sensor: Testing and Inspection

Knock Sensor, Checking

NOTE:
- It is extremely important to keep to the tightening torque of 20 Nm to ensure the knock sensor performs perfectly.
- Only gold-plated contacts may be used when servicing the knock sensor connector contacts.

Special tools and equipment
- Test box VAG 1598/22
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test conditions
- Knock sensor malfunction recognized by On Board Diagnostic, checking and erasing DTC memory DTC Memory Checking and Erasing.

Checking function
- Connect VAG 1551 Scan Tool ((VAG 1552). Start engine and select "Address word" 01 of engine control module. When doing this engine must be running at idling speed. (Connecting scan tool and selecting engine control module [1][2][3]Connecting VAG Scan Tool 1551/1552).

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 8 for function "Read Measuring Value Block" and confirm entry with Q key.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press keys 0, 2 and 2 for "Display group number 22" and confirm entry with Q key.

Indicated on display: (1 to 4 = Display zones)

Read Measuring Value Block 22 ->
1 2 3 4

NOTE: Checking the knock sensor must be performed during a test drive because the diagnosis of the knock sensor is first activated above an engine speed of 3000 RPM and an engine load greater than 3 ms.

Observe the valid safety precautions when carrying out a test drive Technician Safety Information.

- Perform a test drive and check knock control specifications on display (display zones 3 and 4)
Specification (cylinders 1 and 2): 0 to 15 degree CA
- Change to display group 23 as follows:
- Press key 3 ((VAG 1551) or key upper arrow (VAG 1552).

Indicated on display: (1 to 4 Display zones)

Read Measuring Value Block 23 ->
1 2 3 4

- Check knock control specifications on display (display zones 3 and 4)
Specification (cylinders 3 and 4): 0 to 15 degree CA

If the specifications are obtained:
- Press -> key.
- Press keys 0 and 6 for "End Output" function and confirm input with Q key.
- Switch ignition off.

If the specifications are not attained:
Checking resistances and wiring







- Separate 3 pin connector to knock sensor (KS) 1 -G61- -1-.
- Measure resistance between contacts 1 + 2, 1 + 3 and 2 + 3 at connections to knock sensors.

Specification: Infinite Ohm







- Connect test box VAG 1598/22 to control module wiring harness.
- Check wiring between test box and 3 pin connector for open circuit using wiring diagram.
Contact 1 + socket 68
Contact 2 + socket 67
Contact 3 + socket 67
Wire resistance: Max. 1.5 Ohm
- Check additional wires at socket 67 for short to sockets 60 and 68.
Specification: Infinite Ohm

If no wiring malfunction is detected:
- Loosen knock sensor and tighten again to 20 Nm.
- Carry out test drive.

During the road test the following operating conditions must be fulfilled:
- The coolant temperature must exceed 80 degree C.
- When the temperature is reached, the operating conditions
Idling
Part throttle
Wide open throttle
Overrun
must be attained several times.
- At wide open throttle the speed must exceed 3500 RPM.
- Again check control module DTC memory.

If the malfunction is still present:
- Replace knock sensor (KS) 1 -G61-.