P0455 on a 2018 Volkswagen Atlas

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 Volkswagen Atlas

Ranked from 455 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank breach or manufacturing defect
High severity
Multiple complaints on this exact vehicle describe a melted/holed fuel tank, fuel leaking underneath the tank, and a misplaced in-tank suction-jet weld — large enough leaks to fail the EVAP large-leak monitor outright.
Reported in 4 NHTSA complaints
Parts:fuel tank
2
Charcoal canister crack
Medium severity
Two complaints on this vehicle describe canister replacement tied to stalling/EVAP-related fault codes; a significant breach reads as a large leak.
Reported in 2 NHTSA complaints
Parts:charcoal canister
3
Purge valve stuck open
Medium severity
One complaint documents the EVAP purge control failing outright, which holds the system at atmospheric pressure and fails the large-leak test.
Reported in 1 NHTSA complaint
Parts:purge valve
4
Gas cap missing, loose, or badly worn
Low severity
A cap that isn't sealing at all is the classic large-leak trigger and the first thing to rule out.
Common cause
Parts:gas cap
5
Disconnected or grossly cracked EVAP hose
Medium severity
A fully detached or badly split vapor line creates an obvious large leak rather than a small one.
Common cause
Parts:EVAP hose
6
Vent valve stuck open
Medium severity
An open vent valve prevents the system from ever building the vacuum/pressure needed to pass the large-leak monitor.
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