P0455: Evaporative Emission System Large Leak Detected
The fuel vapor system has a large leak or is not sealing at all.
Severity: 1 of 4
Safe to drive in most cases. Check the gas cap right away. If you smell strong raw fuel or see dripping fuel, park it and get it inspected, because that may be a liquid leak rather than a vapor leak.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0455 means
The EVAP self test could not build or hold vacuum. That usually means something is wide open: a missing or loose gas cap, a disconnected hose, or a valve stuck open.
Common causes (cheapest likely first)
- Gas cap missing, loose, or not clicked. By far the most common reason.
- Disconnected or split EVAP hose. Often near the canister or engine.
- Vent valve stuck open. Common failure.
- Purge valve stuck. Can cause hard starting after refueling too.
- Damaged canister or filler neck. Physical damage or rust.
Symptoms
- Check engine light
- Fuel smell
- Hard start right after refueling (with a stuck purge valve)
DIY difficulty: Easy to moderate
Start with the cap and visible hoses.
Tools: OBD-II scanner, Gas cap, Flashlight, Basic hand tools
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Gas cap | $10 to $35 | 0.0 to 0.1 h | $10 + 0.0 × $110 = $10 $35 + 0.1 × $190 = $54 |
| EVAP hose | $15 to $80 | 0.3 to 1.0 h | $15 + 0.3 × $110 = $48 $80 + 1.0 × $190 = $270 |
| Vent or purge valve | $25 to $150 | 0.3 to 1.5 h | $25 + 0.3 × $110 = $58 $150 + 1.5 × $190 = $435 |
Watch a repair video
How To Fix Large Evap Leaks On Your Car P0455 (Scotty Kilmer). Third-party video, loads from YouTube (privacy-enhanced mode) only when you press play. Procedures vary by vehicle. Search YouTube for “P0455 fix” videos.
P0455 by make
Brand specific notes: Toyota, Ford, Chevrolet. Other makes: the code works the same way; see all makes.
Repair manuals
Step-by-step service manuals with torque specs and wiring diagrams:
Haynes manuals Chilton manuals
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Related codes
Check for recalls
Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.
FAQ
I tightened the gas cap. Why is the light still on?
The computer needs to rerun its test, which can take a few days of driving.
Is P0455 an emergency?
No, unless you smell or see liquid fuel.