P04CA code meaning
Fuel Fill Door Open Request Sensor/Switch Circuit Low
Powertrain system Generic code P04xx codes Check engine light
What P04CA means
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.
P04CA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P04CA
- Fuel button has no effect, door does not open
- Refuelling system message in the instrument cluster
- Refuelling only via emergency release
Common causes of P04CA
- Most likelyButton supply circuit open (Ford: supply circuit or splice)
- Most likelyButton line shorted to ground
- PossibleFuel button faulty
- Less likelyModule
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel door open request switchSwitch wiringEngine control module
What each part of P04CA means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| CA | The exact fault in that area. |
What to do next
- Note P04CA and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P04CA
What does P04CA mean?
P04CA means "Fuel Fill Door Open Request Sensor/Switch Circuit Low". 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). It is a generic code, so it means the same on every make.
Is it safe to drive with P04CA?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P04CA fail an emissions test?
Yes, it can. P04CA is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P04CA to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P04CA clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.