OBD-II code · Powertrain (generic)
P0499 EVAP System Vent Valve Control Circuit High
Same as P0498 with the control line open or shorted to supply. The evaporative system captures fuel vapor from the tank and purges it into intake; leaks or stuck purge valves leak hydrocarbons and cause emissions failures.
Is it safe to drive with P0499?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl line open
- PossibleControl line shorted to supply
- Less likelyConnector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.4–1.2 h
- Emissions test
- Likely to fail
- Parts involved
- Evap Vent Valve, Evap Vent Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.