P04F1
EVAP System Purge Line Performance
Generic OBD-II
Real-world scan data
Seen in
87
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Appears alongside · share of P04F1 scans
U27B9in 58.6% of scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check for any loose or damaged hoses in the EVAP system purge line
- Inspect the purge valve for proper operation and replace if necessary
- Clean or replace the EVAP canister if it is contaminated with debris or fuel
- Inspect the fuel tank for any cracks or leaks and repair as needed
- Perform a smoke test to detect any leaks in the EVAP system and repair accordingly
Common causes
Most likely first
- Loose or damaged gas cap
- Faulty purge valve
- Leaking or cracked EVAP system hoses or tubes
- Faulty EVAP canister
- Malfunctioning fuel tank pressure sensor
How to diagnose & fix
Work through it in order
- Check engine light illuminated
- Difficulty starting the vehicle
- Decreased fuel efficiency
- Strong fuel odor
- Increased emissions
Read & clear P04F1 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.