P0455 on a 2017 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 2017 Ford Fusion Energi

Ranked from 1,030 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank pressure sensor / vent valve fault (gas-tank humming/honking, hard restart after refueling)
High severity
Multiple complaints describe a recurring humming/honking/sucking noise from the gas tank plus stalling and hard restarts after refueling -- consistent with a vent valve or tank pressure sensor fault that prevents the EVAP system from sealing/venting correctly, which a large-leak test reads as a gross leak.
Reported in 7 NHTSA complaints
Parts:fuel tank pressure sensor vent valve
2
Failing/stuck canister purge valve
High severity
Multiple complaints describe repeated canister purge valve replacements, including one documented stuck open (excess system vacuum).
Reported in 3 NHTSA complaints
Parts:purge valve
3
Loose, missing, or damaged gas cap
Low severity
The single most common large-leak trigger; confirm the cap clicks fully and the seal is intact.
Common cause
Parts:gas cap
4
Disconnected or badly cracked EVAP/fuel filler hose
Medium severity
A fully detached or split hose produces an obvious large leak; trace the lines from canister to filler neck.
Common cause
5
Cracked charcoal canister housing
Medium severity
A larger split in the canister body causes a gross rather than small leak.
Common cause
Parts:charcoal canister
6
Rusted-through fuel filler neck
Low severity
Advanced corrosion can open a hole large enough to fail the large-leak EVAP test.
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