P0455 on a Mazda: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to drive — this is an emissions leak, not an engine problem. Fix it before your next emissions test.

What P0455 means on a Mazda

On a Mazda, P0455 means the EVAP system has a large leak and fuel vapors are escaping. The engine itself runs fine, so the check engine light is usually the only sign. It's an emissions issue, not a drivability issue.

Is P0455 common on Mazdas?

P0455 is a common EVAP code on Mazdas, especially on CX-5, Mazda3, Mazda6, and CX-9 models with higher mileage. Loose or worn gas caps, cracked EVAP hoses, and aging canister vent valves are the usual culprits. Cold weather can also shrink rubber seals and trigger the code.

Commonly reported on: Mazda3, Mazda6, CX-5, CX-9.

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: Cracked or disconnected EVAP hose
common: Faulty EVAP purge or vent valve
less common: Crack in the charcoal canister or filler neck

How to fix it

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