Powertrain
generic / SAE
P04B9
Fuel Fill Door Position Sensor Circuit Low
Same as P04B8 with the signal voltage below the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / B9
Possible causes
- Signal shorted to ground high
- Connector pins corroded - high contact resistance low
- Harness chafing through insulation low
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 60–250 €
- Estimated time: 0.4–1.2 h
- Component: fuel fill door position sensor
Sources
References
sae:J2012