Checking the fuel gauge (BMW 3 Series E46)

As the fuel level in the tank decreases, the float in the reserve sensor also drops. At the same time, the resistance of the sensor, which has a sliding contact, decreases. The microprocessor in the instrument panel unit, based on the sensor resistance and other data, calculates the fuel level in the tank and outputs the data to the instrument panel. Both sensors are checked in the same way.

Examination

1. Remove the sensor.

2. Connect an ohmmeter to the terminals of the reserve sensor plug.

3. Keep the sensor in the working position. The float is at the bottom and the indicator on the panel shows "Fuel Reserve". The required resistance value: 70±2 Ohm.

4. Rotate the sensor 180° (put it on your head), the float is at the top. The indicator on the panel shows "full".

Required value:

• right sensor 402±6 Ohm
• left sensor 362±6 Ohm

5. If necessary, replace the damaged reserve sensor as a set.