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.
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.
Common causes
- high
Signal shorted to supply
One of the most commonly reported causes for this code — check this first.
Typical part cost: $70-240
- low
Connector pins corroded - high contact resistance
Less common, but worth ruling out after the more likely causes.
Typical part cost: $70-240
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P04CB mean?
P04CB means "Fuel Fill Door Open Request Sensor or Switch Circuit High". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P04CB?
signal shorted to supply; connector pins corroded - high contact resistance; supply wire pinched against b+ source — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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