P0440 on a Hyundai: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to drive — this is a general emissions-system fault, not a mechanical issue — but fix it before your next emissions test.

What P0440 means on a Hyundai

On a Hyundai, P0440 means the engine computer detected a general problem in the evaporative emission (EVAP) system that holds fuel vapors from the tank. It is the catch-all EVAP code, less specific than the leak-size codes P0442, P0455, and P0456, so it often appears with other EVAP codes. The car usually drives and performs normally.

Is P0440 common on Hyundais?

P0440 is very common on Hyundais, and a loose or worn gas cap is by far the most frequent trigger on this brand. As the car ages, cracked EVAP hoses and a failing purge or vent valve become more likely. It is an emissions fault, not a drivability fault.

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

Symptoms

Check engine light on
Possible faint fuel smell
No drivability symptoms

Common causes

most common: Loose, missing, or worn gas cap
common: Cracked or disconnected EVAP hoses
common: Faulty purge or vent valve
less common: Small leak in the charcoal canister

How to fix it

Fix	DIY?	Typical cost
Tighten or replace the gas cap	Yes	$10–30
Replace cracked EVAP hoses	Yes	$20–80
Smoke test the EVAP system to find the leak	Mechanic	$50–150
Replace the purge or vent valve	Yes	$50–140