P04B0
Refueling Vapor Control Valve Circuit Open
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.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Open in harness or solenoid windingCommon
- Pin pushed back out of connector bodyLess likely
- Cracked solder joint inside the module or sensorLess likely
Parts involved
- Refueling Vapor Valve
- Vapor Canister
- Fuel Filler Assembly
P04B0 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.