P0455 on a Hyundai: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to drive — this is an emissions leak, not an engine problem, but fix it before your next emissions test.

What P0455 means on a Hyundai

On a Hyundai, P0455 means the engine computer has detected a large leak in the evaporative emission (EVAP) system, so fuel vapors are escaping. On Hyundais, a loose or damaged gas cap is the most common cause, though a cracked EVAP hose or a failing vent valve can trigger it too.

Is P0455 common on Hyundais?

P0455 shows up on Hyundais like the Elantra, Sonata, Tucson, and Santa Fe, usually on higher-mileage cars. The gas cap is the cheapest thing to check first, and a smoke test will find anything bigger.

Commonly reported on: Elantra, Sonata, Tucson, Santa Fe.

Symptoms

Check engine light is on
Possible fuel smell
No driving symptoms
Emissions test failure

Common causes

most common: Loose, missing, or damaged gas cap
common: Disconnected or cracked EVAP hose
common: Faulty EVAP purge or vent valve
less common: Crack in the charcoal canister

How to fix it

Fix	DIY?	Typical cost
Tighten or replace the gas cap	Yes	$10–30
Inspect and reconnect or replace cracked EVAP hoses	Yes	$10–60
Have a smoke test performed to find the exact leak	Mechanic	$50–150
Replace a faulty purge or vent valve	Yes	$30–120