P0455 on a 2017 Toyota Corolla

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 Toyota Corolla

Ranked from 187 NHTSA owner complaints filed for this vehicle.

Sort by:

1
EVAP charcoal canister fault
Medium severity
This owner's check-engine light was tied to 17 stored 'emission control failure' codes; canister faults are the most common source of a large multi-code EVAP cluster on this platform.
Reported in 1 NHTSA complaint
Parts:charcoal canister
2
EVAP purge valve stuck open
Medium severity
This owner reported 5 stored 'emissions and fuel' codes; a purge valve stuck open holds the system at atmospheric pressure, tripping the large-leak monitor.
Reported in 1 NHTSA complaint
Parts:EVAP purge valve
3
Loose or faulty gas cap
Low severity
The classic large-leak cause; a cap not fully seated fails the gross-leak test outright.
Common cause
Parts:fuel filler cap
4
EVAP vent valve stuck open
Medium severity
A vent valve stuck open prevents the system from ever sealing for the leak test, a common large-leak cause.
Common cause
Parts:EVAP vent valve
5
Disconnected or split EVAP hose/line
Medium severity
A hose knocked loose during service or split from age is large enough to fail the gross-leak test.
Common cause
6
Corroded or rusted-through fuel filler neck
Low severity
Severe corrosion can perforate the filler neck enough to register as a large leak.
Common cause

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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