Audi Workshop Service and Repair Manuals

Checking knock sensors Special tools and workshop equipment required t  Portable multimeter -V.A.G 1526C- t  Adapter set -V.A.G 1594C- t  121-pin adapter cable -V.A.G 1598/31- Fitting location ⇒ Overview of fitting locations → Chapter

Checking wiring of knock sensors   Note t  Electrical checking of knock sensor 1 -G61- and knock sensor 2 -G66- (i.e. the actual sensors) is not possible. t  Always use gold-plated contacts when repairing the knock sensor connectors. t  Exact compliance with the tightening torque of 20 Nm is crucial to proper operation of the knock sensors. t  Check for corrosion of the connector from the knock sensor to the wiring harness.

–  Unplug the connector of knock sensor 1 -G61--1-/knock sensor 2 -G66--2- in the engine compartment.

–  Check all three contacts at the knock sensor connector for mutual short circuit (contacts 1+2, 1+3, 2+3). t  Specification: ∞ Ω (no continuity) - there must be no connection between any of the contacts. –  If there is, replace the knock sensor. –  If no short circuit is found, check the wiring of the knock sensors. Checking wiring between knock sensors and engine control unit –  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter. –  Check for open circuit and short to earth or positive in the following wiring:

l  Knock sensor 1 -G61- (cylinder 1/2)

Connector Contact	Test box -V.A.G 1598/31- Socket
1 (signal)	106
2 (earth)	99
3 (screen)	108

l  Knock sensor 2 -G66- (cylinder 3/4)

Connector Contact	Test box -V.A.G 1598/31- Socket
1 (signal)	107
2 (earth)	99
3 (screen)	108

–  Eliminate open circuit in wiring/short circuit if necessary.