P0455 on a 2015 Ford Fusion Energi

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 Fusion Energi

Ranked from 995 NHTSA owner complaints filed for this vehicle.

Sort by:

1
EVAP purge or vent valve stuck open
Medium severity
Multiple owners had a purge valve replaced (some tied to code P1450) after experiencing stalling/hard starts after fueling, which is consistent with a large-leak-sized fault in the purge/vent circuit.
Reported in 8 NHTSA complaints
Parts:purge valve vent valve
2
Loose, missing, or damaged gas cap
Low severity
A gross leak code like P0455 is most often a cap left loose or not clicked to full seal; one owner's gas cap "burping" and hard-restart symptom fits a cap/seal that isn't holding pressure.
Reported in 1 NHTSA complaint
Parts:gas cap
3
Cracked, split, or disconnected EVAP hose/line
Medium severity
A fully detached or split line produces a large, easily detected leak rather than the smaller leak flagged by P0442.
Common cause
4
Charcoal canister crack or housing failure
Low severity
A significant crack in the canister housing opens a large leak path that fails the EVAP monitor quickly.
Common cause
Parts:charcoal canister
5
Rusted-through fuel filler neck
Medium severity
Advanced corrosion can perforate the filler neck enough to constitute a large leak rather than a small one.
Common cause
Parts:fuel filler neck
6
EVAP vent valve stuck open
Medium severity
A vent valve that won't seat lets the fuel tank vent to atmosphere continuously, a large enough leak path to fail the P0455 gross-leak monitor.
Common cause
Parts:vent valve

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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