BMW E30 speedometer not working or reading wrong
E30 speedometer not working – where is the fault usually found?
Most often the cause is the connector or wire of the speed sensor at the rear of the car. The sensor is near the plug under the rear bumper. The wire may be broken or pinched in its clip. The sensor itself rarely fails. When the sensor gives no signal, the speed shows zero and the odometer shows infinity.
The speedometer works only occasionally or stops working in wet weather. What should I check?
1. Unplug and clean the sensor connector and check the condition of the wire. 2. Check that the wire is not pinched in the clip. 3. Check fuse number 12. 4. If replacing the sensor does not help, the fault may be a poor connection in the instrument cluster or a cold solder joint on the circuit board.
The speedometer reads too high – what is the real speed?
The speedometer can read several percent too high. In one measured car, 200 km/h on the speedometer corresponded to about 184 km/h of real speed. Tyre pressures and the condition of the car, for example, affect the error. The most reliable way to check is a GPS measurement.