P04F0EVAP System High Load Purge Line A Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Turbocharged engines also purge the charcoal canister under boost, through a high-load line to the compressor inlet via a venturi; check valves keep boost out of the EVAP system, and CARB requires this path to be monitored. P04F0 checks it: Ford (2020–23, replacing P144C) runs the test once per trip under boost with the vent closed and purge open, and sets the code if tank pressure rises faster than 0.5 or 1 inH2O/s or the vacuum rate is out of range, within 5–10 s. VW, Audi and Bentley monitor the line with their own pressure sensor.
- What you may notice
- Check engine light on
- Usually no change in driving
- Possibly fuel smell, EVAP readiness not set
- Likely causes
- LikelyCheck valve in the purge line leaking, stuck open, fitted wrongly or missing
- PossibleHigh-load purge line to the turbo or venturi off, cracked or blocked
- PossiblePurge line pressure sensor wrongly connected or faulty (VW group)
- RarePurge valve or venturi faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.