With Manufacturer's Scan Tool

Knock Sensors, Checking







Special tools and workshop equipment required

- V.A.G 1526 A.
- V.A.G 1594 A.
- V.A.G 1598/31.

NOTE:
- The knock sensors -G61- and -G66- cannot be tested electrically by themselves.
- Use only gold-plated terminals when repairing the cable connectors for the knock sensors.
- To ensure that the knock sensors function properly it is important to keep exactly to the specified tightening torque of 20 Nm.
- Check connector between knock sensor and wiring harness for corrosion.

Testing knock sensor wiring







- Disconnect knock sensor 1 -G61- connector -Pos. 1- or knock sensor 2 -G66- connector -Pos. 4-.







NOTE: To gain access to the connector, remove coolant expansion tank bolt -arrow- and move expansion tank to the side. Fuel hoses remain connected.







- Test for short between all three terminals in knock sensor connector (terminals 1+2, 1+3, 2+3).
- Specified value: infinite Ohms (no continuity) the wiring must not be connected to each other.
- If there is a connection between terminals, install a new knock sensor.

If no malfunction is found:

Checking wiring from knock sensors to ECM

- Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect ECM.







- Check for open circuit, short to ground, or short to positive in following wiring connections:
- Knock sensor 1 -G61- (cylinders 1 and 2)

Connector Test box VAG 1598/31
terminal Socket

1 (signal) 106
2 (ground) 99
3 (screening) 108







- Knock sensor 2 -G66- (cylinders 3 and 4).

Connector Test box VAG 1598/31
terminal Socket

1 (signal) 107
2 (ground) 99
3 (screening) 108

- Repair any open/short circuit as necessary.