What does it mean?
This code covers a fuel filler door position sensor or switch signal that behaves erratically rather than failing outright. The module watches the input and sees it flicker between states, change without any physical door movement, or drop out for a moment and return. Because the module uses this input to decide when it is safe to seal the tank and when refuelling can begin, a jumpy signal is treated as a fault even if the door is working perfectly at the time of the test. Faults of this kind are almost always caused by a poor connection rather than a defective sensor: a loose terminal, a chafed wire or a wet connector all produce exactly this pattern. Chasing the sensor first is usually a waste of effort until the connections have been proven.
Symptoms
- MIL (check engine lamp) that appears and clears on its own
- Occasional messages about the fuel filler door with nothing visibly wrong
- Fuel filler door status in live data that flickers when the body is flexed or the door is tapped
- Evaporative monitors that sometimes complete and sometimes abort
- Complaint occurring mainly on rough roads, after a car wash or in wet weather
Likely causes
- Loose or spread terminals in the switch connector, losing contact with vibration
- Water intrusion into the connector, common because the switch sits in an exposed area
- Wiring chafed where the harness passes through the body panel grommet into the filler area
- Partly broken conductor inside the insulation, opening and closing as the vehicle moves
- Worn switch contacts that bounce when the door moves slightly
- Corroded ground connection shared with other body circuits, giving an unstable reference
- Loose door or worn hinge letting the door move enough to trigger the switch while driving
How to fix it
- Compare the conditions in freeze frame data from each occurrence to find a pattern such as rough road, rain or car wash
- Graph the switch input on a scan tool while wiggling the connector, the harness and the door itself to reproduce the dropout
- Open and inspect the connector for moisture, corrosion, damaged seals and terminals that have lost their grip
- Check the harness where it passes through the body grommet into the filler recess, which is the most common chafe point
- Perform a voltage drop test on the signal and ground legs rather than only checking continuity
- Verify the door and hinge are tight enough that normal driving cannot move the door against the switch
- Repair the connection or replace the switch as indicated, then drive under the recorded conditions to confirm the signal stays stable