P0455 on a 2018 Chevrolet Traverse

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 Chevrolet Traverse

Ranked from 452 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Stuck-open canister purge valve/solenoid
High severity
The same purge valve/solenoid fault reported repeatedly in this batch (including a valve that failed twice after replacement) can open a large enough path to fail the large-leak test.
Reported in 3 NHTSA complaints
Parts:purge valve purge solenoid
2
EVAP flow/non-purge malfunction (companion P0496)
Medium severity
Two complaints document an explicit P0496 code alongside stalling/rough-running, indicating a flow-path problem in the same EVAP system.
Reported in 2 NHTSA complaints
3
Capless fuel filler flap/seal failure
Medium severity
This Traverse's capless filler design is flagged in this batch as leak-prone; a stuck or worn flap can leave a large opening to atmosphere.
Reported in 1 NHTSA complaint
Parts:fuel filler neck seal
4
Disconnected, cracked, or loose large EVAP hose/line
Medium severity
A complaint of fuel odor in the cabin is consistent with a larger EVAP line breach rather than just a pinhole leak.
Reported in 1 NHTSA complaint
Parts:EVAP hose
5
Charcoal canister crack
Low severity
A significantly cracked canister housing can open a leak path large enough to fail the large-leak monitor.
Common cause
Parts:charcoal canister
6
EVAP vent valve stuck open
Low severity
A vent valve that won't close prevents the system from sealing at all, guaranteeing a large-leak result.
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