P0442 on a Mazda: Causes, Fixes & Repair Cost

🟢 Low severity · drivable

Safe to keep driving — this is an emissions leak, not a mechanical issue — but fix it before your next emissions test.

What P0442 means on a Mazda

On a Mazda, P0442 means the engine computer found a small leak in the evaporative emission (EVAP) system that stores fuel vapors from the tank. Mazda monitors the fuel system for small pressure losses, which is what sets this code. The car typically drives and performs normally.

Is P0442 common on Mazdas?

P0442 is a common emissions code on Mazdas, frequently starting with a loose gas cap and then, with age, cracked EVAP hoses or a worn purge valve. The small rubber and plastic lines in the EVAP system are the usual leak points. It is an emissions issue, not a drivability issue.

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

Symptoms

Check engine light on
Possible faint fuel smell
No drivability symptoms

Common causes

most common: Loose, missing, or failing gas cap
common: Cracked or disconnected EVAP hoses
common: Faulty purge valve
less common: Small leak in the charcoal canister or fuel tank

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 valve	Yes	$50–140