P0455 on a 2021 Ford Escape Hev

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 2021 Ford Escape Hev

Ranked from 326 NHTSA owner complaints filed for this vehicle.

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1
Cracked fuel injector allowing significant fuel vapor escape (open NHTSA recall 25S76/25V467)
High severity
The same open recall for cracked fuel injectors that generates persistent fuel odor and fire-risk complaints is large enough in several reports to register as a large EVAP leak rather than a small one.
Reported in 6 NHTSA complaints
Parts:fuel injector fuel rail
2
Fuel filler cap/door not sealing or left open
Low severity
An owner reports the fuel door will not close, which is large enough an opening to commonly present as a large EVAP leak rather than the small-leak code; verify the door latches and the cap threads properly.
Reported in 1 NHTSA complaint
Parts:fuel filler cap fuel filler door hinge
3
EVAP purge valve stuck open
Medium severity
Owner-reported stalling immediately after refueling was traced to the EVAP purge valve, consistent with a valve that will not reseat and lets tank pressure vent to atmosphere.
Reported in 1 NHTSA complaint
Parts:EVAP purge valve
4
EVAP canister vent/solenoid valve failure
Medium severity
Multiple solenoid replacements failed to resolve a fuel-vapor complaint, suggesting a recurring vent/solenoid or wiring fault rather than a one-off part failure.
Reported in 1 NHTSA complaint
Parts:EVAP vent valve
5
Disconnected or split EVAP hose/line
Medium severity
A fully detached or split EVAP line produces a large-leak code; inspect connections between the tank, canister, and purge valve for a hose that has popped off or cracked through.
Common cause
Parts:EVAP hose/line
6
Cracked charcoal canister
Medium severity
A significantly cracked canister housing cannot hold vapor pressure and is a common large-leak source.
Common cause
Parts:charcoal canister
7
Rusted or perforated fuel filler neck
Medium severity
A larger rust hole in the filler neck (versus a hairline crack) is a classic large-leak cause and is common on higher-mileage or salt-belt vehicles.
Common cause
Parts:fuel filler neck

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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