P04B9
Fuel Fill Door Position Sensor/Switch Circuit Low
Generic OBD-II
Common symptoms
What you'll notice
- Check the wiring and connectors for any damage or loose connections
- Inspect the fuel fill door position sensor/switch for any signs of damage or malfunction
- Replace the fuel fill door position sensor/switch if necessary
- Reset the vehicle's onboard computer system to clear the error code and see if it returns
Common causes
Most likely first
- Faulty fuel fill door position sensor/switch
- Loose or damaged wiring/connectors in the fuel fill door position sensor/switch circuit
- Malfunctioning fuel fill door position sensor/switch
- Corrosion or debris affecting the fuel fill door position sensor/switch operation
- Defective powertrain control module (PCM) interfering with the fuel fill door position sensor/switch circuit
How to diagnose & fix
Work through it in order
- Fuel filler door does not open or close properly
- Warning light on the dashboard indicating a problem with the fuel filler door
- Inability to insert or remove the fuel nozzle properly during refueling
- Fuel odor inside the vehicle, especially near the fuel filler area
- Malfunctioning power door locks or power door release for the fuel filler door
Read & clear P04B9 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.