P0455 on a 2019 Ford F 150 Supercab

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 2019 Ford F 150 Supercab

Ranked from 953 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Purge valve stuck closed causing excessive vacuum and fuel tank collapse
High severity
The fuel tank purge valve issue documented on this truck caused performance problems and an imploded (collapsed) fuel tank - a severe EVAP system fault well beyond a small leak.
Reported in 1 NHTSA complaint
Parts:purge valve fuel tank
2
Cracked or ruptured fuel line from the canister to the fuel rail
High severity
A metal fuel line from the canister area to the high-pressure rail ruptured on this exact truck, pouring fuel and breaching the fuel/vapor system.
Reported in 1 NHTSA complaint
Parts:fuel line
3
Missing, loose, or badly damaged gas cap
Medium severity
A missing or badly seated cap is the classic large-leak cause.
Common cause
Parts:gas cap
4
Cracked or split charcoal canister
Medium severity
A cracked canister housing creates a large, unrecoverable vapor leak.
Common cause
Parts:charcoal canister
5
Corroded or rusted fuel filler neck
Medium severity
Rust-through at the filler neck is a common large-leak source at higher mileage.
Common cause
Parts:fuel filler neck
6
Cracked or split EVAP vent line
Medium severity
A split vent line/hose creates an open path large enough to fail the large-leak monitor.
Common cause
Parts:evap hose

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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