P0440 on a Ford: 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 Ford

On a Ford, 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 Fords?

P0440 is a common EVAP code on Fords like the F-150, Escape, Explorer, and Focus, especially as the gas cap seal and EVAP hoses age. A loose or worn gas cap is the most common cause, followed by faulty purge valves and small cracks in EVAP hoses. Ford's EVAP system monitors closely, so even a tiny crack can set the code.

Commonly reported on: F-150, Escape, Explorer, Focus.

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 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 purge valve	Yes	$50–140