Powertrain, generic · Auxiliary emission controls

P04BB Fuel Fill Door Lock Control Circuit/Open

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). P04BB concerns the lock circuit: the module detects an open circuit in the output to the door actuator or its relay, which CARB requires for outputs. 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

Open control wire or connector at the door actuator
Actuator motor or solenoid open internally
Actuator supply, fuse or relay not working
Driver in the module

Symptoms

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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–350
Time0.5–2 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

P04BFP04BCP04BDP04BEP04B5P04B6

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