Knock sensors, checking

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Knock Sensors, Checking

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Special tools and equipment

VAG1526 A
VAG1594 A
VAG1598/31

NOTE:

The Knock Sensor (KS) 1 -G61- and Engine Coolant Temperature (ECT) sensor -G62- cannot be tested by themselves electrically.
Use only gold-plated terminals when repairing the cable connectors for the knock sensors.
Make sure that the knock sensors function properly it is important to keep to the specified tightening torque of 20 Nm.
Check connector between knock sensor and wiring harness for corrosion.

Testing knock sensor wiring

Disconnect connector of relevant knock sensor. See Figure or Figure.

Fig 2: 3-Pin Connector & Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Test for short between all three terminals in knock sensor connector (terminals 1+2, 1+3, 2+3).

Specified value: ∞ Ω (no continuity) - the wires 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 engine control module

Connect test box VAG1598/31 to wiring harness for engine control module; do not connect engine control module. Refer to Wiring and component check with test box VAG 1598/31 .
Check for open circuit and short to ground/positive or ground in following wiring connections:

Fig 3: Identifying 3-Pin Connector Terminals 1 & 3

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Knock Sensor (KS) 1 -G61- (Bank 1)

Connector Terminal	Test box VAG1598/31 Socket
1 (signal)	106
2 (ground)	99
3 (screening)	108

Knock Sensor (KS) 2 -G66- (Bank 2)

Connector Terminal	Test box VAG1598/31 Socket
1 (signal)	107
2 (ground)	99
3 (screening)	108

Repair any open/short circuit as necessary.