P0455 on a 2016 Hyundai Tucson Fuel Cell

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 Hyundai Tucson Fuel Cell

Ranked from 1,536 NHTSA owner complaints filed for this vehicle.

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1
EVAP-system fault directly confirmed on this vehicle
Medium severity
One owner's own scan explicitly returned a P0455 code on this vehicle, confirming a real large-leak EVAP fault rather than an intermittent/borderline trip.
Reported in 1 NHTSA complaint
2
Purge control valve failure/stuck
Medium severity
Owner had the purge solenoid replaced along with the fuel pump while chasing an intermittent driveability fault, indicating past purge-circuit trouble on this vehicle.
Reported in 1 NHTSA complaint
Parts:purge valve
3
Fuel/vapor odor reported by an owner consistent with a system leak
Low severity
Owner reported a persistent gas smell inside the cabin alongside other driveability complaints, consistent with a leak large enough to be perceptible.
Reported in 1 NHTSA complaint
4
Loose, missing, or damaged gas cap
Low severity
A large-leak EVAP code is very commonly a gas cap that isn't sealing; check first before condemning other components.
Common cause
Parts:gas cap
5
Cracked or disconnected EVAP hoses/lines
Medium severity
A larger, more obvious leak point (disconnected or split hose) is the typical trigger for the large-leak variant of this code.
Common cause
6
Charcoal (EVAP) canister cracks
Medium severity
A cracked or corroded canister housing is a common source of a large EVAP leak.
Common cause
Parts:EVAP canister
7
Rusted fuel filler neck
Low severity
A rusted-through filler neck creates an obvious, larger leak path near the gas cap seal.
Common cause
Parts: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