P0455 on a 2017 Chevrolet Malibu Eco

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 Chevrolet Malibu Eco

Ranked from 687 NHTSA owner complaints filed for this vehicle.

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1
Failed EVAP canister vent solenoid
Medium severity
The same EVAP vent control circuit fault (P0498/P0449) documented on this vehicle, calling for canister vent solenoid replacement, is large enough to also register as a gross/large leak.
Reported in 1 NHTSA complaint
Parts:EVAP canister vent solenoid
2
Restricted or disconnected fuel tank vent path
Medium severity
The reported inability to fill the tank past 7/8 capacity points to a stuck or blocked vent path, which large-leak testing can also expose if a hose has since disconnected.
Reported in 1 NHTSA complaint
Parts:fuel tank vent valve
3
Loose or missing gas cap
Low severity
A cap that isn't tightened, is cross-threaded, or is missing entirely produces a large, immediate EVAP leak.
Common cause
Parts:fuel cap
4
Disconnected or badly cracked EVAP hose/line
Medium severity
A fully disconnected or split EVAP line (rather than a pinhole) is the typical cause of a large-leak code.
Common cause
Parts:EVAP hose
5
Purge valve stuck open
Medium severity
A purge valve stuck open lets the EVAP system leak down immediately, failing the large-leak test.
Common cause
Parts:purge valve
6
Cracked charcoal canister housing
Medium severity
A significant crack in the canister housing produces enough leak flow to fail the large-leak EVAP monitor.
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