Engine Speed Sensors

Remove Gray (engine RPM) and Black (ignition timing reference) connectors from bracket near ignition coil. For each connector, check continuity between terminals No. 1 and 2. See Fig 2 . Ohmmeter reading should be 1000 ohms.
If not, replace sensor(s). If reading is correct, check continuity between terminals No. 1 and 3, and terminals No. 2 and 3 for each connector. If ohmmeter reading is not infinity (4), replace sensor(s).

Unplug connector from ECU. Check wiring between harness side of each sensor connector and ECU. See Fig 1 and Fig 2 . Ensure resistance of each wire between ECU and sensor connectors is zero ohm. See ENGINE SPEED SENSOR CIRCUITS table.

ENGINE SPEED SENSOR CIRCUITS

Sensor Terminal		ECU Harness Connector Terminal
Engine RPM (Gray)
1		29
2		11
3		28
Ignition Timing Reference (Black)
1		13
2		12
3		28

Ensure clearance between ignition timing reference sensor and flywheel pin is .43" (1.10 mm). If engine speed sensors and wiring circuits are okay, replace control unit.

Fig 1: Identifying ECU Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

Fig 2: Engine Speed Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

NOTE: Terminal identifications for Hall Effect sending unit are located on connector.