Engine Speed Sensor: Testing and Inspection

Engine Speed (RPM) Sensor, Checking

The engine speed (RPM) sensor -G28- is a speed and reference mark sensor. 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
- VAG 1551 Scan Tool or VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/22
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test sequence







- Separate gray 3-pin connector -1- to engine speed sensor.
- Measure sensor resistance between contacts 2 + 3 of connector to sensor.
Specification: 480 to 1000 Ohms
- Check sensor for short between contacts 1 + 3 and 2 + 3.
Specification: Infinite Ohms

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

If no sensor malfunction is detected:







- Connect test box VAG 1598/22 to control module wiring harness.







- Check wiring between test box and 3 pin connector for open circuit according to wiring diagram.
Contact 1 + socket 56
Contact 2 + socket 63
Contact 3 + socket 67
Wire resistance: Max. 1.5 Ohm
- Additionally check wires for short to one another.

If no wiring malfunction is detected:
- Check sensor wheel for proper seating and damage.

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

If no malfunction is detected on sensor wheel:
- Replace engine control module.