P0455 on a 2016 GMC Canyon

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 2016 GMC Canyon

Ranked from 267 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Chafed fuel line / leak near fuel tank (missing skid plate or AC-line contact)
High severity
Fuel leaking from a hose rubbing on the AC line and from a tank missing its protective skid plate are both large enough breaches to fail the EVAP monitor and produce a noticeable fuel odor.
Reported in 2 NHTSA complaints
Parts:fuel line fuel tank skid plate
2
Rodent-damaged fuel line
High severity
Soy-based line coating attracts wildlife on this truck; a chewed-through fuel line is a large, easily detected breach of the sealed fuel system.
Reported in 1 NHTSA complaint
Parts:fuel line
3
Loose, missing, or damaged gas cap
Low severity
The most common general cause of a large EVAP leak code; check the cap seal and threads first.
Common cause
Parts:fuel filler cap
4
EVAP vent valve stuck open
Medium severity
A vent valve that won't seat lets the system bleed down instead of holding pressure, which reads as a large leak.
Common cause
Parts:EVAP vent valve
5
Disconnected or split EVAP vapor line
Medium severity
A hose popped off a fitting or split open is one of the most common large-leak findings on a smoke test.
Common cause
Parts:EVAP vapor hose
6
Cracked EVAP canister
Medium severity
A cracked canister housing is a large enough breach to fail the monitor outright.
Common cause
Parts:EVAP 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