Knock Sensor: Testing and Inspection
Diagnostic Procedures
Knock Sensors, Checking
• Contact surfaces between knock sensor and cylinder block must be free of corrosion, dirt and grease.
• 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, testers and auxiliary items required
• Multimeter (VAG1526) or multimeter (VAG1715)
• Connector test kit (VAG1594)
• Wiring diagram
Test requirements
• mounting bolts of knock sensors tightened to 20 Nm.
• Ignition switched off.
Test sequence
Cylinder bank 1
- Disconnect the 3-pin harness connector to Knock Sensor (KS) 1 (G61) (arrow).
Cylinder bank 2
- Disconnect the 3-pin harness connector to Knock Sensor (KS) 2 (G66) (arrow).
Cylinder bank 1 and 2
• Cylinder bank 1 = in direction of travel, right.
• Cylinder bank 2 = in driving direction, left.
• Before disconnecting harness connectors, mark allocation to component.
Checking resistances
- Measure resistance between terminals 1 + 2, 1 + 3 and 2 + 3 at the connections to the respective knock sensors.
Specified value: infinite ohms
If specified value is not obtained:
- Replace the respective knock sensor:
Cylinder bank 1
• Knock Sensor (KS) 1 (G61) ,
Cylinder bank 2
• Knock Sensor (KS) 2 (G66).
- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code.
If specified value is obtained:
- Check wires according to wiring diagram.
Checking wiring
- Connect test box to control module wiring harness , connect test box for wiring test.
- Check wires between test box and 3-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms
Cylinder bank 1
Cylinder bank 2
Cylinder bank 1 and 2
- Also check wires for short circuit to each other.
Terminal 1 + socket 108
Specified value: infinite ohms
- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code.
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).