P0455 on a 2015 Ford F 250 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 2015 Ford F 250 Super Crew

Ranked from 296 NHTSA owner complaints filed for this vehicle.

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1
Fuel tank filler neck or EVAP line corrosion/leak near the tank
Medium severity
Owners report a rusted-through fuel line and a severe leak at a fitting on top of the tank; a large breach here is exactly the kind of gross leak this code detects.
Reported in 2 NHTSA complaints
Parts:fuel tank filler neck EVAP line
2
Cracked fuel filter housing allowing vapor/fuel escape
Medium severity
A repeatedly cracking upper fuel filter housing is a large enough opening to fail the gross-leak EVAP test.
Reported in 1 NHTSA complaint
Parts:fuel filter housing
3
Fuel line leak/fitting failure with fuel odor
Medium severity
A reported fuel odor with rapidly falling indicated range suggests a supply-side leak large enough to also fail the EVAP monitor.
Reported in 1 NHTSA complaint
Parts:fuel line
4
Loose, missing, or damaged gas cap
Low severity
A large EVAP leak code is disproportionately caused by a cap left off or with a failed seal; check this before anything else.
Common cause
Parts:gas cap
5
Disconnected or split EVAP hose
Low severity
A hose knocked loose during service (e.g., after fuel-system repairs) leaves a wide-open path that reads as a large leak.
Common cause
Parts:EVAP line
6
Purge or vent valve stuck open
Low severity
A valve stuck fully open prevents the tank from ever holding vacuum/pressure, which the PCM reports as a large leak.
Common cause
Parts:purge valve vent valve
7
Charcoal canister crack
Low severity
A significant crack in the canister housing is large enough to fail the gross-leak check.
Common cause
Parts:charcoal canister

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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