Powertrain, generic · Auxiliary emission controls

P04BC Fuel Fill Door Lock Control 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). P04BC concerns the lock circuit: the actuator is driven but the expected reaction is missing – the door or lock sensor reports no change within the time window. A separate lock output exists only on actuators that drive actively in both directions; spring-return actuators have only the unlock circuit. 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 or door mechanically blocked (ice, dirt, bent door, cap tether)
Actuator worn or stiff
Lock or door sensor reporting wrongly
Door held or pressed by hand during actuation

Symptoms

  • Filler door does not open or lock as commanded
  • Refuelling system message in the instrument cluster
  • Possibly check engine light

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–250
Time0.3–1.5 h

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

Parts involved

fuel fill door lock actuatoractuator wiringengine control module

Related codes

P04C0P04BBP04BDP04BEP04B5P04B6

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