OBD-II code · Powertrain (generic)
P04B3 Refueling Vapor Control Valve Performance Stuck Open
The refueling vapor control valve is stuck open. Vapor pathways meant to be closed except during refueling stay permanently open, distorting EVAP leak diagnostics and allowing vapor flow even with the fuel cap closed.
Is it safe to drive with P04B3?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyValve stuck open due to debris or weak spring
- Less likelyCarbon or debris buildup preventing free movement
- Less likelyComponent wear with age - mechanical play
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.8–1.8 h
- Emissions test
- Likely to fail
- Parts involved
- Refueling Vapor Valve
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.