P0455 on a 2017 Ford Explorer

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 2017 Ford Explorer

Ranked from 1,669 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Purge valve failure/sticking
Medium severity
Purge valve replaced as part of a documented EVAP repair; another report of the purge valve sticking and causing RPM flares.
Reported in 2 NHTSA complaints
Parts:purge valve
2
Cracked fuel-tank sending-unit/fuel-pump gasket leaking gasoline near the tank top
High severity
Dealer-confirmed cracked gasket at the sending unit/fuel pump letting gasoline and fumes escape right next to the exhaust -- a large enough leak that the dealer treated it as a fire-safety repair.
Reported in 1 NHTSA complaint
Parts:fuel tank fuel pump
3
Damaged or pinched fuel line
High severity
A misplaced intake hose clamp rubbed through the metal fuel line, producing a raw-fuel leak onto the engine.
Reported in 1 NHTSA complaint
Parts:fuel line
4
Charcoal canister crack / EVAP component degradation
Medium severity
Charcoal canister and tubing were replaced along with sensors while chasing a persistent EVAP fault on this vehicle.
Reported in 1 NHTSA complaint
Parts:charcoal canister
5
Loose or missing fuel filler cap
Low severity
The most common large-leak trigger industry-wide; check first since it costs nothing to rule out.
Common cause
6
Cracked or split EVAP line
Medium severity
A fully split or disconnected vapor line produces a large, easily detected leak.
Common cause
7
Rusted or corroded filler neck
Medium severity
Corrosion perforation of the filler neck can be large enough to fail the large-leak test outright.
Common cause
Parts:fuel filler neck

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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