P0455 on a 2016 GMC Yukon

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 Yukon

Ranked from 265 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Chafed or leaking fuel line near the tank
High severity
A documented case of the fuel supply line chafing through near the top of the tank produced a sizeable fuel smell/leak, the type of gross leak this code flags.
Reported in 1 NHTSA complaint
Parts:fuel line
2
Underlying fuel system leak producing fuel odor
High severity
A separate complaint of fuel-pump leakage with a persistent gas smell is consistent with a large fuel/vapor leak feeding this code.
Reported in 1 NHTSA complaint
3
Loose, missing, or damaged gas cap
Low severity
By far the most common P0455 trigger -- an unseated, cross-threaded, or cracked cap fails a large-leak EVAP test.
Common cause
Parts:gas cap
4
Cracked or disconnected EVAP vent/purge hose
Medium severity
A split or popped-off EVAP hose creates a large, easily detected leak path; trace the hoses from the canister to the intake and tank.
Common cause
Parts:EVAP hose
5
Vent valve stuck open
Medium severity
A vent valve stuck fully open leaves the system essentially open to atmosphere, which reads as a large leak.
Common cause
Parts:vent valve
6
Cracked charcoal canister
Medium severity
A significantly cracked canister housing produces a large-leak-sized fault rather than a small one.
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