Powertrain, generic · Auxiliary emission controls

P04C4 Fuel Fill Door Lock Position Sensor/Switch Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

On plug-in hybrids with a sealed, pressurised tank, pressing the fuel button (open request) starts a refuelling mode: the module opens the tank valve, releases the pressure into the charcoal canister and only then unlocks the filler door via an electric actuator (Ford patent). The lock position sensor in the actuator reports locked or unlocked – not to be confused with the door position sensor (open or closed, P04B7–P04BA). P04C4 means its feedback is electrically valid but does not fit the commanded state – for example unlock commanded and the sensor still reports locked – or does not change. No manufacturer document available to us uses this code; the description follows CARB's rules for input and output components and patents on the door actuator.

Likely causes

Actuator does not travel fully (blocked or worn)
Switch in the actuator worn or misadjusted
Door distorted, latch does not engage
Module

Symptoms

  • Filler door does not unlock or lock reliably
  • Refuelling system message
  • Possibly check engine light

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel fill door lock position switchfuel fill door lock actuatorsensor wiringengine control module

Related codes

P04C3P04C5P04C6P04C7P04B8P04BC

References: law.cornell.edu, patents.google.com, patents.google.com.