Checking knock sensor wiring

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.

NOTE:

Knock Sensor (KS) 1 -G61- and Knock Sensor (KS) 2 -G66- themselves cannot be electrically tested.
When servicing terminals in harness connector of knock sensors, use only gold-plated terminals.
For the Knock Sensors to function properly, it is important for tightening torque to be exactly 20 N.m.
Check harness connector from knock sensor to wiring harness for corrosion.

Disconnect harness connector for Knock Sensor (KS) 1 -G61- (item 1) or Knock Sensor (KS) 2 -G66- (item 4).

Fig 1: Disconnecting Harness Connector For Knock Sensor (KS) -G61- Or Knock Sensor (KS) -G66-
Courtesy of AUDI OF AMERICA, INC.

NOTE: Coolant reservoir screw (arrow) must be removed and coolant reservoir must be placed to the side in order to access harness connector. The coolant hoses remain connected.

Fig 2: Removing Coolant Reservoir Screw
Courtesy of AUDI OF AMERICA, INC.
Check all three terminals at knock sensor connector for short circuit to each other (terminal 1+2, 1+3, 2+3).

Fig 3: Identifying Knock Sensor Connector Terminals
Courtesy of AUDI OF AMERICA, INC.
- Specified value: INFINITY Ω (no continuity) - the wires must not have any connection to each other.
If there is a connection, replace knock sensor.

If no malfunction can be found: