OBD-II code · Powertrain (generic)
P04CB Fuel Fill Door Open Request Sensor or Switch Circuit High
Same as P04C8 with the signal voltage shorted to supply or constantly high. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P04CB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal shorted to supply
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.4–1 h
- Emissions test
- Usually unaffected
- Parts involved
- Fuel Fill Door Request Switch
Related codes
- P04C8Fuel Fill Door Open Request Sensor or Switch Circuit
- P04C9Fuel Fill Door Open Request Performance Stuck Off
- P04CAFuel Fill Door Open Request Sensor or Switch Circuit Low
- P04CCFuel Fill Door Open Request Sensor or Switch Circuit Intermittent or Erratic
- P04CDFuel Fill Door Open Request Sensor or Switch Stuck On
- P04CEEGR Temperature Sensor C Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.