Powertrain, generic · Auxiliary emission controls

P04CD Fuel Fill Door Open Request Sensor/Switch Stuck On

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). P04CD means the button is detected as pressed for an unusually long time. Mitsubishi's Outlander PHEV from 2023 sets it if the button line stays at 1 V or less for 13.5 minutes – a jammed button or a short to ground. Mitsubishi shows a 'refuelling system service required' message for these codes and gives no drive-cycle pattern.

Likely causes

Fuel button mechanically jammed or sticking
Button line shorted to ground
Moisture or dirt in the button
Module

Symptoms

  • Fuel button has no effect, door does not open
  • Refuelling system message in the instrument cluster
  • Refuelling only via emergency release

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–200
Time0.3–1.5 h

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

Parts involved

fuel door open request switchswitch wiringengine control module

Related codes

P04C8P04C9P04CAP04CBP04CCP04BF

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