Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Knock Sensor , checking
This procedure is used to diagnose Knock Sensor (KS) 1 G61 and Knock Sensor (KS) 2 G66.
Special tools, testers and auxiliary items required
- Multimeter V.A.G 1526 or equivalent.
- Test Box 105 Pin VAG1598/42.
- Adapter Lead Vag1598/39 VAG1598/39.
- Adapter cable V.A.G 1598/39-1.
- Cylinders 1, 2 are monitored by Knock sensor (KS) 1 -G61-. Cylinders 3,4 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
- Mounting bolt of Knock Sensor (KS) 1 G61/Knock Sensor (KS) 2 G66 tightened to 20 Nm.
- Fuses for Engine Control Module (ECM) J623 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 sequence
- Remove engine cover - arrows -.
- 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.
- Disconnect the electrical harness connector from Knock Sensor (KS) 1 G61 - 1 - or Knock Sensor (KS) 2 G66 - 2 -.
- Using the Multimeter V.A.G 1526 A or equivalent, check Knock Sensor (KS) 1 G61 or Knock Sensor (KS) 2 G66 electrical connector terminals 1+2 for resistance for a short to each other.
Specified value: 0 Ω (No Continuity).
If the specification is not obtained:
- Replace respective Knock Sensor (KS) 1 G61/Knock Sensor (KS) 2 G66 → 15 - ENGINE - CYLINDER HEAD, VALVETRAIN .
If the specification is obtained:
- Connect the test box 1598/42 to the wiring harness of the Engine Control Module (ECM) J623. → 24 - MULTIPORT FUEL INJECTION (MFI) . The ECM is not connected.
- Using the Test Box 105 Pin VAG1598/42 and Multimeter V.A.G 1526 A or equivalent, check the following wiring connections for an open circuit.
| Component | Terminal | Test box socket |
|---|---|---|
| Knock Sensor (KS) 1 G61 | 1 | 39 |
| 2 | 54 | |
| 3 | 52 | |
| Knock Sensor (KS) 2 G66 | 1 | 9 |
| 2 | 24 | |
| 3 | 52 |
Specified resistance 1.5 Ω max.
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunctions are found in the wiring:
- Replace the Engine Control Module (ECM) J623 → Engine Control Module (ECM) J623 , replacing .
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..
- If the DTC memory was erased, generate readiness code..
- End diagnosis and switch ignition off.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.