P0455 on a 2018 Toyota Camry

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 Toyota Camry

Ranked from 727 NHTSA owner complaints filed for this vehicle.

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1
Fuel filler neck / tank seal leak (vapor escaping near the fuel door)
Medium severity
Several owners independently describe fuel vapor condensing and dripping near the filler pipe/fuel door in hot weather — large enough to run down the side of the car.
Reported in 2 NHTSA complaints
Parts:fuel filler neck
2
Gas cap not sealing or missing
Medium severity
One owner reported fuel actively leaking out around the fuel cap whenever the car sat overnight regardless of tank level — exactly the kind of open path that trips the large-leak code.
Reported in 1 NHTSA complaint
Parts:gas cap
3
Fuel door release/latch mechanism failure
Low severity
A flimsy fuel-door release mechanism was reported failed since purchase, which can keep the filler door/cap from seating and sealing correctly.
Reported in 1 NHTSA complaint
Parts:fuel door latch
4
EVAP purge valve stuck open
Medium severity
One owner had the purge valve replaced three times for a check-engine light and gas smell on every fill-up, with the issue persisting.
Reported in 1 NHTSA complaint
Parts:purge valve
5
EVAP vent valve stuck open
Low severity
A vent valve stuck open prevents the system from ever sealing, commonly showing up as the large-leak code.
Common cause
Parts:vent valve
6
Disconnected, split, or crushed EVAP hose
Medium severity
A fully detached or split EVAP line creates a large, unrestricted leak path.
Common cause
Parts:EVAP hose
7
Charcoal canister crack
Low severity
A significantly cracked canister housing can leak enough vapor to register as a large leak.
Common cause
Parts:EVAP 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