P0440 on a Lexus: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

You can keep driving — this is a general emissions-system fault, not an engine problem — but fix it before your next emissions test.

What P0440 means on a Lexus

On a Lexus, 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 car usually drives and performs normally.

Is P0440 common on Lexuss?

P0440 is a common emissions code on Lexus models, and like other Toyota-family vehicles, a loose or failing gas cap is the most frequent trigger. With age, cracked EVAP hoses and worn purge or vent valves become more likely. It is an emissions concern, not a mechanical failure.

Commonly reported on: RX, ES, NX, GX.

Symptoms

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

Common causes

most common: Loose, missing, or failing gas cap
common: Cracked or disconnected EVAP hoses
less common: Faulty purge or vent valve
rare: 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	$60–150