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
Knock Sensor (KS) 1 (G61)
- Disconnect black 3-pin harness connector for knock sensor 1 (arrow).
Knock Sensor (KS) 2 (G66)
- Disconnect black 2-pin harness connector for knock sensor 2 (arrow).
Checking wires to Engine Control Module (ECM)
- Connect test box to control module wiring harness , connect test box for wiring test.
Knock Sensor (KS) 1 (G61)
- 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
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: infinite ohms
If no malfunctions are found in wires:
- Replace Knock Sensor (KS) 1 (G61).
- Erase DTC memory of Engine Control Module (ECM) , Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code.
Knock Sensor (KS) 2 (G66)
- Check wires between test box and 2-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: infinite ohms
If no malfunctions are found in wires:
- Replace Knock Sensor (KS) 2 (G66).
Final Procedures
After the 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 ] Diagnostic Modes 01 - 09.
2. If necessary, erase the DTC memory. Refer to --> [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
3. If the DTC memory was erased, generate readiness code. Refer to --> [ Readiness Code ] Readiness Code.