P0455 on a 2019 Chevrolet Equinox

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 2019 Chevrolet Equinox

Ranked from 292 NHTSA owner complaints filed for this vehicle.

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1
Leaking or corroded fuel tank / filler neck
High severity
Several owners report fuel visibly dripping from the top or rear of the tank area, including cases tied to a prior recall on this platform; a tank-area leak is a large, direct vapor-leak path for the EVAP system.
Reported in 3 NHTSA complaints
Parts:fuel tank fuel filler neck
2
Faulty EVAP purge/vent valve or canister assembly
High severity
One owner had the EVAP canister replaced for this exact code, only for the light to return, indicating the purge/vent hardware (not just the canister) is the actual fault on this vehicle.
Reported in 1 NHTSA complaint
Parts:EVAP canister purge valve vent valve
3
Loose, missing, or worn gas cap
Low severity
A large EVAP leak code is very often just a gas cap that wasn't tightened or has a failed seal; this is the first thing to rule out.
Common cause
Parts:fuel filler cap
4
Disconnected, cracked, or split EVAP hose/line
High severity
A sizable gap anywhere in the vapor lines (often at a quick-connect fitting) produces the large-leak signature rather than the small-leak one.
Common cause
Parts:EVAP hose
5
Stuck-open vent valve/canister vent solenoid
Medium severity
If the vent valve can't close, the EVAP system can never build the vacuum/pressure needed to pass the leak test.
Common cause
Parts:vent valve
6
Leaking or corroded fuel tank/filler neck
High severity
A pinhole or seam leak in the tank itself is a large, unmistakable leak path for the EVAP monitor.
Common cause
Parts:fuel tank fuel filler neck

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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