P0455 on a 2019 Ford Escape

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 Escape

Ranked from 563 NHTSA owner complaints filed for this vehicle.

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1
Failed/stuck-open EVAP purge valve
Medium severity
Documented on this vehicle: a P0496 purge-valve-sticking-open code, and a separate purge valve failure causing the fuel system to vapor-lock at fueling — a valve stuck open leaves the system essentially unsealed, large enough to register as a large leak.
Reported in 2 NHTSA complaints
Parts:EVAP purge valve
2
Confirmed EVAP system leak (dealer-diagnosed)
Medium severity
One owner had an EVAP leak directly confirmed by a Ford dealership, indicating a real leak path large enough to fail the monitor.
Reported in 1 NHTSA complaint
3
Loose or missing fuel filler cap
Low severity
The most common large-leak trigger; a cap that isn't tightened/seated fails the monitor's coarse leak test almost immediately. Most fuel/propulsion complaints on this vehicle are the unrelated EcoBoost coolant-intrusion issue and were excluded here as not code-consistent.
Common cause
Parts:fuel filler cap
4
Disconnected or split EVAP vapor line/hose
Medium severity
A hose popped off a fitting or split open produces an obvious, large vapor leak.
Common cause
Parts:EVAP hose EVAP line
5
EVAP vent valve (CVV) stuck open
Low severity
A vent valve stuck fully open holds the system at atmospheric pressure, read by the monitor as a large leak.
Common cause
Parts:EVAP vent valve
6
Rusted-through fuel filler neck
Low severity
Advanced corrosion can perforate the filler neck outright, producing a leak large enough to set P0455.
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