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P0455

P0455 on a 2015 Ford Fusion

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

Ranked from 1,049 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Canister purge valve (CPV) stuck open, causing a large, continuous EVAP leak

    High severity

    Owners had the purge valve explicitly diagnosed/replaced after code P1450 and stalling right after refueling, including one repeat failure of the same part.

    Reported in 6 NHTSA complaints
    Parts:purge valve
  2. 2

    Fuel vapor odor from a cracked EVAP canister or lines

    Medium severity

    Persistent gasoline smell after fueling and a loud air sound at the filler with no visible leak points to an internal EVAP leak path.

    Reported in 2 NHTSA complaints
    Parts:EVAP canisterEVAP lines
  3. 3

    P1450-type large EVAP leak / restricted fuel tank vent path

    Medium severity

    Code P1450 ("unable to bleed up fuel tank vacuum") was pulled repeatedly along with a burping/sucking gas-cap noise, pointing to a blocked or stuck vent path rather than a simple purge valve.

    Reported in 1 NHTSA complaint
  4. 4

    Loose, cross-threaded, or worn fuel filler cap

    Low severity

    The single most common trigger for a small EVAP leak code; verify the cap clicks fully and the seal is intact before condemning other components.

    Common cause
    Parts:fuel cap
  5. 5

    Canister vent valve stuck closed

    Medium severity

    A vent valve that won't open blocks fresh-air purge flow and can trigger vacuum/pressure-based EVAP faults similar to those reported here.

    Common cause
    Parts:vent valve
  6. 6

    Rusted or corroded fuel filler neck

    Low severity

    Rust-through of the filler neck creates a leak path that a smoke test will reveal; more common on high-mileage, road-salt-exposed vehicles.

    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

1

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.

2

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.

3

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.

4

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.

5

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