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 (KS), checking
The following procedure is used to check Knock Sensor (KS) 1 G61, Knock Sensor (KS) 2 G66, Knock Sensor 3 G198, and Knock sensor 4 G199.
Special tools, testers and auxiliary items required
- Multimeter V.A.G 1526 A or equivalent.
- Adapter Cable (121-Point) VAG1598/31.
- Cylinders 1 and 2 as well as 3 and 4 (bank 1) are monitored by Knock Sensor (KS) 1 G61 and Knock Sensor (KS) 2 G66. Cylinders 5 and 6 as well as 7 and 8 (bank 2) are monitored by Knock Sensor 3 G198 and Knock sensor 4 G199.
- 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 the Knock Sensors and cylinder block must be free of corrosion, dirt and grease.
- Check the Knock Sensors electrical harness connectors for corrosion.
Test requirement
- Ignition switched off.
Checking knock sensor and wiring
- Remove front engine cover - arrows -1- and -2 -.
- Disconnect electrical harness connector - 1 -, - 2 -, - 5 - or - 6 - of the knock sensor to be checked.
1 - Knock Sensor (KS) 1 G61
2 - Knock Sensor (KS) 2 G66
5 - Knock Sensor 3 G198
6 - Knock sensor 4 G199
- Check as follows:
- Using the Multimeter V.A.G. 1526 A or equivalent, check all three terminals of the knock sensor for a short circuit to each other as follows:
| Knock sensor terminals |
|---|
| 1+2 |
| 1+3 |
| 2+3 |
Specified value: 0 Ω (no continuity).
The wiring must not have any connection to each other.
- If there is a connection, replace faulty knock sensor.
If no malfunction can be found:
Check wiring from knock sensors to Engine Control Module (ECM)
- Connect Adapter Cable (121-Point) VAG1598/31 to wiring harness of Engine Control Module (ECM) J623 ; the ECM is not connected. → Diagnostic tester, connecting .
- Using Adapter Cable (121-Point) VAG1598/31 and Multimeter V.A.G 1526 A or equivalent, check the following wiring connections for an open circuit.
- Knock Sensor (KS) 1 -G61-
| Harness connector Terminal | Test box Socket |
|---|---|
| 1 Ground (GND) | 99 |
| 2 (signal) | 106 |
| 3 (shielding) | 108 |
- Knock Sensor (KS) 2 -G66-
| Harness connector Terminal | Test box Socket |
|---|---|
| 1 Ground (GND) | 99 |
| 2 (signal) | 107 |
| 3 (shielding) | 108 |
- Knock Sensor 3 G198
| Harness connector Terminal | Test box Socket |
|---|---|
| 1 Ground (GND) | 99 |
| 2 (signal) | 31 |
| 3 (shielding) | 108 |
- Knock sensor 4 G199
| Harness connector Terminal | Test box Socket |
|---|---|
| 1 Ground (GND) | 99 |
| 2 (signal) | 16 |
| 3 (shielding) | 108 |
Specified value: Wire resistance max 1.5 Ω.
If specification is not obtained:
- Check wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair wiring connection.
If no malfunction can be found:
- Replace Engine Control Module (ECM) J623. → Engine Control Module (ECM) J623, replacing .
Assembly is performed in reverse order of removal. Note the following:
Tighten torque
| Component | Nm |
|---|---|
| knock sensor bolt | 20 |
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
- Check DTC memory..
- If necessary, erase DTC memory..
- If 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.