S4 Quattro Wagon V8-4.2L (BHF) (2008)
Knock Sensor: Testing and Inspection
Knock Sensors, Checking
The following procedure is used to diagnose all Knock Sensors.
Special tools, testers and auxiliary items required
‹› Multimeter.
‹› Wiring diagram.
Test requirements
‹› The mounting bolt of Knock Sensor (KS) 1 (G61)/Knock Sensor (KS) 2 (G66)/Knock Sensor 3 (G198)/Knock Sensor 4 (G199 ) tightened to 20
Nm.
‹› The Motronic Engine Control Module (ECM) ( J623) fuses OK.
‹› Battery voltage at least 12.5 volts.
‹› All electrical consumers such as, lights and rear window defroster, switched off.
‹› Vehicles with automatic transmission, shift selector lever into position " P" or "N".
‹› A/C switched off.
‹› Ground (GND) connections between engine/transmission/chassis OK.
‹› Ignition switched off.
Procedure
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Remove the engine cover with air filter Refer to Fuel Injection and Ignition Repair Information.
‹› Before disconnecting the Knock Sensor electrical harness connectors, mark the component location.
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Disconnect the green Knock Sensor (KS) 1 (G61 ) electrical harness connector- 1 - or the gray Knock Sensor (KS) 2 (G66) electrical harness
connector - 2 -.
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or Knock Sensor 3 (G198)
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or Knock Sensor 4 (G199)