P0455 on a 2018 Jeep Wrangler

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 Jeep Wrangler

Ranked from 1,793 NHTSA owner complaints filed for this vehicle.

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1
Fuel tank, filler neck, or EVAP line leak
High severity
Owners reported gasoline actively leaking/gurgling from the tank area or puddling from above the tank while parked and while driving — large enough leaks to be seen and smelled, consistent with a large EVAP-side leak.
Reported in 2 NHTSA complaints
Parts:fuel tank EVAP hose
2
EVAP canister flooded/saturated from a fuel tank overfill fault
Medium severity
A dealer explicitly determined the fuel tank was 'not taking fuel properly' and had filled the EVAP canister with liquid fuel on one of these vehicles, a failure large enough to register as a big leak.
Reported in 1 NHTSA complaint
Parts:charcoal canister
3
Restricted or faulty EVAP vent valve/fill-limiter
Medium severity
An owner could not fill the tank to rated capacity, pointing to a vent path/valve problem that can also manifest as a large-leak code when the valve fails open instead.
Reported in 1 NHTSA complaint
Parts:vent valve
4
Gas cap not tightened, damaged, or missing
Low severity
The classic and most common cause of a large/gross EVAP leak code.
Common cause
Parts:gas cap
5
Purge valve stuck open
Medium severity
A purge valve stuck open prevents the EVAP system from ever sealing, which the monitor reads as a large leak.
Common cause
Parts:purge valve
6
Cracked or split charcoal canister
Low severity
A significant crack in the canister housing creates a large enough leak path to fail the monitor quickly.
Common cause
Parts: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.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Check Engine Light