What it means
The refueling vapor control valve - typically part of the ORVR or capless fueling system - has an open control circuit. The valve directs fuel vapor from the tank into the canister during refueling and must open when the fuel filler is opened. Without it, vapor escapes during refueling and the system fails leak diagnostics.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The refueling vapor control valve directs displaced tank vapor into the charcoal canister while the vehicle is being refueled. P04B0 sets when the control module detects an open electrical path in the valve circuit, so the valve may not operate when the filler is opened.
Common causes
Most likely first.
- Open in harness or solenoid winding
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine light on
- Fuel vapors may escape during refueling
- Fuel odor around the filler area
- Refueling may be interrupted or difficult
How to diagnose it
- Review freeze-frame and EVAP data for the refueling event or system condition associated with the fault.
- Inspect the refueling vapor valve connector for a loose plug, corrosion, moisture, or a terminal pushed back into the housing.
- Trace the valve harness near the filler and tank for breaks, chafing, or damaged clips.
- Check the valve solenoid winding for an open circuit against the manufacturer's specification.
- Check continuity through the valve control wiring to the module, isolating components as directed by the service information.
Common fixes
- Reconnect the refueling vapor valve plug and secure the harness.
- Repair an open or chafed section of the valve wiring.
- Replace loose, corroded, or pushed-back connector terminals.
- Replace the refueling vapor valve if its winding is open.
Can I keep driving?
Drive cautiously to a repair location if there is no fuel leak, but stop refueling if vapor escapes or the pump repeatedly shuts off. Escaping fuel vapor is a fire concern and can also cause emissions failure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.