With Generic Scan Tool

Check Engine Speed (RPM) Sensor

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
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test sequence
Vehicles with engine code AFP







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

Vehicles with engine code BDF







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

Continuation for all vehicles







- Measure sensor resistance between terminals 2 + 3 at connector to sensor.
Specified value: 480...1000 Ohm
- Check sensor for shorts between terminals 1 + 2 and 1 + 3.
Specified value: infinite Ohm

If specified values are not obtained:
- Replace Engine Speed (RPM) Sensor -G28-:
- Vehicles with engine code AFP, item 25,
- Vehicles with engine code BDF, item 16.







- Check wires between test box and 3-pin connector for open circuit according to wiring diagram.
Terminal 1 + socket 108
- 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 connect test box for wiring test.
Test Box, Connecting For Wiring Test

Terminal 2 + socket 90
Terminal 3 + socket 82
Wire resistance: max: 1.5 Ohm
- Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: infinite Ohm

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-.