P0440 on a Jeep: 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 Jeep

On a Jeep, 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 vehicle usually drives and performs normally.

Is P0440 common on Jeeps?

P0440 is a common EVAP code on Jeeps, starting most often with a loose gas cap. On off-road use, EVAP hoses and the charcoal canister can take hits from rocks or trail debris, and the plastic lines under the body crack as they age. It is an emissions concern, not a mechanical failure.

Commonly reported on: Wrangler, Cherokee, Grand Cherokee, Compass.

Symptoms

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

Common causes

most common: Loose, missing, or failing gas cap
common: Cracked or rubbed-through EVAP hoses
common: Faulty purge or vent valve
less common: Damaged 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 charcoal canister	Yes	$120–280