Fuel Level Sensor "B" Circuit

Possible causes

• CommonFailed fuel level sender in the tank
• CommonWorn sender track - the most common failure on a high-mileage vehicle
• CommonCorroded connector at the tank or under the rear seat
• PossibleDamaged wiring under the vehicle
• PossibleFloat detached or fuel-logged
• PossibleLoss of reference voltage or earth

What you might notice

• Fuel gauge wrong, jumping or stuck
• Range calculation implausible
• Low fuel warning at the wrong level
• Running out of fuel unexpectedly
• Check engine light on

What to check, in order

1. Note that many vehicles have two senders. On a saddle-shaped tank, one sits in each half and the module adds them - so sender "B" failing gives a gauge that reads correctly for part of a tank and wrongly for the rest.
2. Watch the reported level while the tank is filled. A reading that jumps or sticks at one point identifies a worn sender track.
3. Inspect the connector, usually reachable under the rear seat or through a boot floor panel.
4. Check the reference voltage and earth at the sender.
5. Until it is fixed, work by trip mileage rather than by the gauge. Running a tank very low is hard on the fuel pump, which relies on the fuel around it for cooling.