P0455 on a 2012 Ford F 150 Super Crew

P0455 means the EVAP system failed a leak check badly enough that the computer sees a large leak or no pressure/vacuum change.

Not your vehicle? See general P0455 info.

Most common causes on the 2012 Ford F 150 Super Crew

Ranked from 1,717 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Vent or purge valve stuck, causing vapor pressure buildup
Medium severity
One owner reported gasses building up inside the tank enough to cause an audible noise, pointing to a vent/purge valve not venting/sealing correctly.
Reported in 1 NHTSA complaint
Parts:vent valve purge valve
2
Disconnected or cracked EVAP line indicated by a strong fuel odor
Medium severity
One owner reported a strong fuel smell from the vehicle, consistent with a sizable EVAP line leak.
Reported in 1 NHTSA complaint
Parts:EVAP hose
3
Loose, missing, or damaged gas cap
Low severity
The classic large-leak trigger; a cap that won't seal fully sets this code almost immediately.
Common cause
Parts:gas cap
4
Cracked or disconnected EVAP hose
Medium severity
A fully split or unseated line produces the large, unrestricted leak this code is designed to catch.
Common cause
Parts:EVAP hose
5
Cracked charcoal canister
Low severity
A cracked canister housing can't seal the EVAP system enough to pass the large-leak test.
Common cause
Parts:charcoal canister
6
Rusted or corroded filler neck
Low severity
A rusted-through filler neck creates a large, direct leak path to atmosphere.
Common cause

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0455 on your car still needs shop confirmation before any repair.

Common symptoms

Check engine light
Fuel smell
Usually no performance issue
Failed emissions readiness

What to check before replacing parts

Check the gas cap first

Look for: A loose, missing, or cross-threaded cap is by far the most common cause of a large EVAP leak code — if it doesn't click to full tightness or the seal is cracked, that's very likely the whole fault.

Inspect visible EVAP hoses

Look for: A large leak is often obvious: a hose disconnected at a fitting, split open, or chewed through (rodent damage is common) rather than a hairline crack.

Command the purge and vent valves with a scan tool

Look for: A valve that doesn't respond at all when commanded open/closed, or stays open when it should seal, prevents the system from holding pressure/vacuum and reads as a large leak.

Smoke-test the system

Look for: With a large leak, expect an obvious plume of smoke or a clearly audible hiss at the fault location — it should be easy to spot compared to a small-leak diagnosis.

Inspect the canister and filler neck

Look for: A cracked charcoal canister housing or a corroded/rusted-through filler neck (common on older vehicles) can leak enough to prevent the system from ever holding vacuum.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Check Engine Light