Powertrain, generic · Auxiliary emission controls

P04CA Fuel Fill Door Open Request Sensor/Switch Circuit Low

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). P04CA means the button line is below its valid range. Ford's Escape and Corsair 2.5 (2020–26) set it with an open supply circuit to the button, so the door does not open. With buttons that pull to ground (Mitsubishi), a permanently low line appears as stuck on (P04CD) instead.

Likely causes

Button supply circuit open (Ford: supply circuit or splice)
Button line shorted to ground
Fuel button faulty
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

P04C8P04C9P04CBP04CCP04CDP04BF

References: law.cornell.edu, patents.google.com, static.nhtsa.gov.