With Generic Scan Tool

Engine Speed (RPM) Sensor, Checking

Function
The Engine Speed (RPM) Sensor -G28- detects engine speed and reference marks. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.

Recommended special tools and equipment
- V.A.G1526 multimeter or V.A.G1715 multimeter
- V.A.G1594 connector test kit
- Wiring diagram

Test sequence

Vehicles with engine code AWD






- Disconnect gray 3-pin harness connector -1- leading to the engine speed (RPM) sensor.

Vehicles with engine code AWP, AWW






- Disconnect gray 3-pin harness connector to engine speed (RPM) sensor (arrow).

Continue for all vehicles






- Measure sensor resistance between terminals 2 + 3 at connector to sensor.
Specified value: 730 to 1000 Ohms

- Check sensor for short circuit between terminals 1 + 2 and 1 + 3.

Specified value: Infinite Ohms

If specified values are not obtained:
- Replace Engine Speed (RPM) Sensor -G28-
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no DTC is found on sensor:
- Connect test box to control module wiring harness. Test Box, Connecting For Wiring Test






- Check wires between test box and 3-pin connector for open circuit according to wiring diagram
Terminal 1 + socket 108
Terminal 2 + socket 90
Terminal 3 + socket 82
Wire resistance: max: 1.5 Ohms

- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite Ohms

If no malfunctions are found in wires:
- Remove sensor and check sensor wheel for secure fit, damage, and run-out.

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

If nothing seems to be wrong with the sensor wheel:
- Replace Motronic Engine Control Module (ECM) -J220-.