P0455 on a 2018 Ford Edge

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 2018 Ford Edge

Ranked from 779 NHTSA owner complaints filed for this vehicle.

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1
Failing EVAP canister purge valve
Medium severity
A purge valve stuck open or leaking is reported directly in this batch, along with a separately logged P0456 EVAP fault that kept recurring after repair.
Reported in 2 NHTSA complaints
Parts:purge valve
2
Loose, damaged, or missing gas cap
Low severity
A cap that isn't sealing is the single most common large-EVAP-leak trigger; one owner in this batch reports the tank effectively running without a functioning cap.
Reported in 1 NHTSA complaint
Parts:gas cap
3
Physically damaged fuel tank or EVAP line (road debris)
High severity
A hole in the fuel tank from a road-debris impact drained fuel and left a persistent gas smell — a large-leak scenario worth ruling out first.
Reported in 1 NHTSA complaint
Parts:fuel tank EVAP line
4
Cracked EVAP vent or vapor line at the tank during refueling
Medium severity
RPM surging, stalling, and a fuel smell specifically during refueling point at a compromised vapor line or tank-pressure sensor near the filler.
Reported in 1 NHTSA complaint
Parts:EVAP vent valve EVAP hose
5
Charcoal canister crack
Medium severity
A cracked canister can leak enough vapor to fail the large-leak portion of the EVAP monitor test.
Common cause
Parts:charcoal canister
6
Corroded or rusted filler neck
Low severity
Advanced corrosion can open a large enough gap at the filler neck to fail the large-leak test.
Common cause
Parts:filler neck
7
EVAP vent valve stuck open
Medium severity
A vent valve that fails open prevents the system from sealing at all during the leak test, presenting as a large leak.
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