Knock Sensor: Testing and Inspection

Knock sensors, checking


NOTE:
- For the knock Sensors to function properly, it is important for tightening torque to be exactly 20 Nm.
- Use only gold-plated terminals when servicing terminals in harness connector of knock sensors.


Special tools and equipment
- VAG 1598/31 adapter cable
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test requirement
- On Board Diagnostic (OBD) must have recognized a malfunction at one or both of the knock Sensors (KS).

Test sequence

Engine code AWM
- Connect V.A.G 1551 scan tool (VAG 1552). Start engine and select the Engine Control Module (ECM) using address word 01. (connecting scan tool and selecting ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551 Scan Tool", Testing and Inspection

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -4- to select "Basic Setting" function 04. Press -Q- button to confirm input.

Indicated on display:


Basic setting HELP
Enter display group number XXX


- Press buttons -0-, -2- and -8- to select "Display group number 28". Press -Q- button to confirm input.

Indicated on display:


System in basic setting 28 ->
1 2 3 4


- Use VAG 1788/10 speed adjuster tool to adjust engine RPM to at least 2600 RPM:
- Maintain engine speed until indication in display field 4 jumps from "Test OFF" to "Test ON".
- Continue to maintain engine speed until display field 4 indicates specified value "Syst. OK".

If specified values are obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.

If specified values are not obtained:
- Check resistances and wiring:

Checking resistances and wires

I - Engine code ATW
II - Engine codes AUG, AWM


- Disconnect 3-pin harness connector to Knock Sensor (KS) 1 -G61- (green, item no.1) and/or 3-pin harness connector to Knock Sensor (KS) 2 -G66- (blue, item no. 2).
- Measure resistance between terminals 1 + 2, 1 + 3, and 2 + 3 at connectors to knock sensors. Specification: Infinity Ohms

If specified value is not obtained:







- Replace knock Sensor(s)

If specified value is obtained:







- Connect VAG 1598/31 adapter cable to control module wiring harness. Engine Control Module (ECM) is not connected.
- Check wiring between test box and 3-pin connector for open circuit according to wiring diagram.
G61: G66:
Terminal 2 + socket 106 107
Terminal 2 + socket 99 99
Terminal 3 + socket 108 108

Wire resistance: max: 1.5 Ohms

- Check wires for shorts among one another.

If no malfunctions are found in wires:
- Loosen the Knock Sensor (KS) and then retighten it to 20 Nm.
- Perform a road test.

The following operating conditions must be obtained during road test:
- Coolant temperature must rise to above 80 °C.
- Once the temperature is reached, the operating conditions
Idle
Partial throttle
Wide Open Throttle (WOT)
Deceleration
must be reached several times each.
- Engine speed must be increased to above 3500 RPM during Wide Open Throttle (WOT).
- Check control module's DTC memory again.

If complaint persists:
- Replace Knock Sensor(s)