With Manufacturer's Scan Tool

Engine Speed (RPM) Sensor -G28-, Checking

Function
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, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1526 Hand multimeter or VAG 1715 multimeter
- VAG 1594 Adapter set
- VAG 1598/31 test box
- Electrical Wiring Diagrams

Test sequence







- Separate grey 3-pin connector -arrow-to Engine Speed (RPM) Sensor.







- Measure sensor resistance between connector terminals 2 and 3 to sensor.
Specification: 480 to 1000 ohms
- Check sensor for short circuit between terminals 1 and 2 as well as 1 and 3.
Specification: infinity ohms

If the specifications are not obtained:
- Replace Engine Speed (RPM) Sensor -G28-, item 16.
- Check DTC memory, repair malfunctions if necessary and then erase DTC memory.
Reading Diagnostic Trouble Codes

- Read readiness code. If the DTC memory has been erased or the Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes

If no sensor Diagnostic Trouble Code (DTC) is detected:
- Remove wiper arms and cowl panel:







- Connect VAG 1598/31 test box to control module wiring harness. The Motronic Engine Control Module (ECM) -J220- remains disconnected.







- Check wiring for open circuit between test box and 3-pin connector referring to Electrical Wiring Diagrams.
Terminal 1 and socket 108
Terminal 2 and socket 90
Terminal 3 and socket 82
Wire resistance: max. 1.5 ohms
- Additionally check wiring for short to one another, to vehicle ground (GND) and to battery positive.
Specification: infinity ohms

If no wiring malfunction is detected:
- Remove sensor and check sensor wheel for secure mounting, 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 no Diagnostic Trouble Code (DTC) is detected on sensor wheel:
- Replace Motronic Engine Control Module (ECM) -J220-.
- Check DTC memory, repair malfunctions if necessary and then erase DTC memory.
Reading Diagnostic Trouble Codes

- Erase learned values and adapt Motronic Engine Control Module (ECM) -J220- again.
- Read readiness code. If the DTC memory has been erased or the Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes