P0440 on a Nissan: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to drive — this is a general emissions-system fault, not an engine problem. Fix it before your next emissions test.

What P0440 means on a Nissan

On a Nissan, P0440 means the engine computer detected a general problem in the evaporative emission (EVAP) system that captures 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 engine usually runs and drives normally.

Is P0440 common on Nissans?

P0440 shows up on Nissans like the Altima, Rogue, Sentra, and Pathfinder, most often as the gas cap seal and EVAP hoses age. A loose or worn gas cap is the most common cause, followed by small cracks in EVAP hoses and faulty vent or purge valves. It is a common code on higher-mileage Nissans.

Commonly reported on: Altima, Rogue, Sentra, Pathfinder.

Symptoms

Check engine light is on
Possible faint fuel smell
Usually no driving symptoms

Common causes

most common: Loose, missing, or damaged gas cap
common: Faulty EVAP vent or purge valve
common: Small leak in an EVAP hose or fitting
less common: Small crack in the charcoal canister

How to fix it

Fix	DIY?	Typical cost
Tighten or replace the gas cap	Yes	$10–30
Inspect and replace cracked EVAP hoses	Yes	$15–80
Have a smoke test performed to find the exact leak	Mechanic	$50–150
Replace a faulty vent or purge valve	Yes	$40–160