P0455
EVAP system large leak detected
Severity: MonitorCheck engine light came on after getting gas
Severity: Monitor
A light that comes on soon after refuelling is most often a gas cap that was left loose or not clicked shut, which affects emissions but not how the car drives.
It gets more serious if:
- Inspect soon: Inspect soon if the car is hard to start, stalls or idles roughly after refuelling, or you keep smelling fuel around the car.
- Stop: Stop driving if you smell strong raw fuel or see fuel leaking: pull over, get everyone out of the car, and have it collected rather than driven.
- Stop: Stop if the check engine light is flashing: that is misfire bad enough to damage the catalytic converter. Pull over safely away from anything flammable, switch off and let it cool. If it flashes again after a restart, have the car taken in or drive gently and slowly only to the nearest repair shop as the owner's manual directs.
How to tell what's causing it
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The light is steady, the car drives normally, and the cap was loose, not clicked, or left off.
A loose cap lets the EVAP system leak and the leak test catches it. Tighten the cap until it clicks; the light should go out by itself after some driving once the test passes.
Points to: Fuel (gas) cap, P0457, P0455
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The cap was tight, but the light stays on after several days and the code is a small or very small leak.
A worn cap seal can cause a small leak, but small leaks often come from hoses or seals elsewhere, which usually need a smoke test to find.
Points to: P0442, P0456, Fuel (gas) cap
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The engine is hard to start, stumbles or stalls right after filling up.
A purge valve stuck open can flood the engine with vapour after refuelling; a Ford bulletin prescribes replacing the purge valve for this complaint on some models.
Points to: EVAP canister purge valve, P0496
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You smell strong raw fuel or see fuel dripping.
This is a fuel leak, not just a vapour fault, and leaked fuel near an ignition source can catch fire. Do not drive; have the car collected.
Codes that go with it
Sources and review
- OBD consumer brochure: Do you drive a 1996 or newer car or light truck? (EPA420-F-02-016)
- What To Do With the Check Engine Light (EPA420-F-00-041)
- Frequently Asked Questions About On-Board Diagnostics (EPA 420-F-97-003)
- 2021 Tacoma Quick Reference Guide
- Owner's Manual (online): Malfunction Indicators
- Vapor Trails: Finding & Fixing Evaporative System Faults (Bob Pattengale)
- Could a Loose Gas Cap Be Causing Your Check Engine Light Problem?
- Ford technical service bulletin: hard start/no start or loss of rpm after refuelling (2013 Escape, 2013-2014 Fusion and MKZ)
- Ford Safety Recall 18S32 Supplement #3 (canister purge valve)
- Owner notification, NHTSA Recall 20V-112 (2020 Nissan Versa fuel tank leak)
- Interim owner notice, NHTSA Recall 20V-700 (2020-2021 Toyota Supra potential fuel tank leak)
- Final Regulation Order: 13 CCR §1968.2, Malfunction and Diagnostic System Requirements (OBD II), 2004 and subsequent model-year passenger cars, light-duty trucks and medium-duty vehicles (2015 amendments)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
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