Engine Speed Sensor: Testing and Inspection

Engine Speed (RPM) Sensor, Checking

The engine speed (RPM) sensor (G28) is a speed and reference mark sender. The engine will not start if there is no speed signal. If the speed signal fails when the engine is running, it will cause the engine to stall immediately.

Special tools and equipment
- Scan tool VAG 1551 or vehicle system tester VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test sequence







- Separate grey 3 pin connector -1- to engine speed (RPM) sensor.
- Measure sender resistance between contacts 2 + 3 of connector to sender.
Specification: 730 - 1000 ohms
- Check the sender for short between contacts 1 + 2 as well as 1 + 3.
Specification: Infinity ohms

If the specifications are not obtained:
- Replace engine speed (RPM) sensor (G28).

If no sender fault is detected:







- Connect test box VAG 1598/31 to control module wiring harness. The engine control module remains disconnected.
- Check wiring between test box and 3-pin connector for open circuit using wiring diagram.
Contact 1 + socket 108
Contact 2 + socket 90
Contact 3 + socket 82
Wire resistance: Max. 1.5 ohms
- Additionally check wires for short to one another.

If no wiring fault is detected:
- Remove sender and check sender wheel for secure fit, damage and run-out.


NOTE: There is a larger gap on the sender wheel. This gap is the reference mark and does not mean that the sender wheel is damaged.


If no fault is detected on sender wheel:
- Replace engine electronics control module.