Engine Speed Sensor: Testing and Inspection

Engine Speed sensor (RPM), checking

NOTE:

Engine Speed sensor G28 is a speed and reference mark sensor. The engine will not start without a speed signal. If the speed signal fails while the engine is running, the engine will stall immediately.

Special tools, testers, measuring instruments and auxiliary items required

- VAG 1551/1552 Scan Tool with VAG 1551/3B adaptor cable
- VAG 1598/22 Test Box
- Fluke 83 Multimeter
- VW 1594 Adaptor kit
- Wiring diagram

Test sequence

- Disconnect gray 3-pin Engine Speed sensor harness connector -arrow-.






- Measure resistance between terminals 1 + 2 of connector -1-
- Specification: 400 to 1000 Ohms
- Check sensor for shorting between terminals 1 + 3 and 2 + 3
- Specification: Infinity Ohms

If specifications not obtained:
- Replace Engine Speed sensor G28.

If Engine Speed sensor OK

- Connect VAG 1598/22 Test Box to Engine Control Module harness connector.







- Check wiring for open circuit between Test Box and 3-pin harness connector -2- using Wiring diagram.

Terminal 1 + socket 56
Terminal 2 + socket 63
Terminal 3 + socket 2
Wire resistance: Max. 1.5 Ohms

- Check wires for shorting to one another.
- Specification: Infinity Ohms

If wiring OK
- Remove sensor and check sensor wheel for secure fit, damage and run-out.

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 sensor wheel OK
- Replace Engine Control Module.