P04DF
EVAP System Purge Control Valve A Performance/Stuck Open
Generic OBD-II
Common symptoms
What you'll notice
- Inspect and clean the EVAP system purge control valve
- Replace the EVAP system purge control valve
- Check and repair any vacuum leaks in the EVAP system
- Ensure proper electrical connection and wiring integrity for the control valve
- Have a smoke test performed to detect and repair any leaks in the EVAP system
Common causes
Most likely first
- Faulty or stuck open EVAP system purge control valve
- Loose or damaged EVAP system hoses or lines
- Defective EVAP system pressure sensor
- Faulty or malfunctioning EVAP system canister vent valve
- Blockage or restriction in the EVAP system charcoal canister
How to diagnose & fix
Work through it in order
- Difficulty starting the vehicle
- Decreased fuel efficiency
- Check Engine light illuminates
- Rough idle or stalling
- Fuel odor coming from the vehicle
Read & clear P04DF yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.