EVAP System Leak Detection Pump Stuck On
The EVAP leak detection pump stays running when commanded off. Relay welded or driver stuck on. 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.
Affected components
- Evap leak detection pump
- Wiring harness
- Ecm
Common causes
- High likelihood: Relay contacts welded
- Medium likelihood: Output driver stuck on
- Low likelihood: Carbon or debris buildup preventing free movement
Possible symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.