P0455 on a 2011 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 2011 Ford Edge
Ranked from 1,801 NHTSA owner complaints filed for this vehicle.
- 1
Cracked fuel tank or rollover valve (large leak)
High severitySeven owners in this batch had the plastic fuel tank crack at the rollover/vent valve or its mounting strap; a crack of this size produces a large-leak fault rather than a pinhole leak.
Reported in 7 NHTSA complaints - 2
Capless filler neck seal or flap failure
Medium severityA torn or stuck-open sealing flap in the capless filler system leaves a wide-open path to atmosphere rather than a pinhole leak — one owner in this batch was told this is a known issue on this generation.
Reported in 1 NHTSA complaintParts:capless filler neck seal - 3
Missing or badly unseated gas cap
Low severityThe first thing to check for a large/gross EVAP leak code — a cap that's off, cross-threaded, or torn.
Common causeParts:gas cap - 4
Disconnected or split EVAP hose / quick-connect fitting
Medium severityA hose that's popped off or split open produces a large, easily smoke-tested leak.
Common causeParts:EVAP hose - 5
Purge or vent valve stuck open
Medium severityA valve stuck fully open leaves the system essentially vented to atmosphere at all times.
Common cause - 6
Cracked charcoal canister housing (larger crack)
Medium severityA larger crack or split in the canister case produces a leak big enough to trip the large-leak threshold rather than the small-leak one.
Common causeParts:EVAP charcoal canister
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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.
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