P0456 on a Hyundai: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to drive — a very small fuel vapor leak won't affect the engine, but fix it before an emissions test.

What P0456 means on a Hyundai

On a Hyundai, P0456 means the computer detected a very small leak in the fuel vapor system. A fuel cap that wasn't tightened until it clicked is the most common reason this code appears.

Is P0456 common on Hyundais?

P0456 is one of the most common EVAP codes on Hyundais, and it usually shows up right after a fuel stop. Most owners solve it with the gas cap, while others need a smoke test to find a tiny hose or valve leak.

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

Symptoms

Check engine light is on
No change in how the car drives
Occasional faint fuel smell

Common causes

most common: Fuel filler cap not fully tightened or worn seal
common: Leaking EVAP purge valve
common: Small leak in an EVAP hose or O-ring
less common: Tiny crack in the charcoal canister

How to fix it

Fix	DIY?	Typical cost
Retighten the fuel cap until it clicks, then clear the code	Yes	$0–30
Have a smoke test performed to find the exact leak	Mechanic	$50–150
Replace the EVAP purge valve if it is the leak source	Yes	$40–120