P0442 Code: Evaporative Emission Control System Leak Detected (Small Leak)

🟢 Low severity · drivable

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

What P0442 means

The evaporative emission (EVAP) system, which captures fuel vapors from the tank, has a small leak. It's an emissions issue and rarely affects how the vehicle runs.

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: Small leak in an EVAP hose or fitting
common: Faulty EVAP purge or vent valve
less common: Small crack in the charcoal canister or fuel tank

How to fix it

Fix	DIY?	Typical cost
Tighten or replace the gas cap	Yes	$10–30
Have a smoke test performed to find the exact leak	Mechanic	$50–150
Replace a faulty purge or vent valve	Yes	$30–120

Frequently asked questions

Can I drive with a P0442 code?

Yes. It's an emissions leak and doesn't affect drivability. Just fix it before your next emissions inspection.

Is P0442 usually just the gas cap?

Often yes. A loose or bad gas cap is the most common cause, so tighten or replace it first before spending on diagnosis.

How much does it cost to fix a P0442?

As little as $10–$30 for a gas cap, or $50–$150 for a smoke test plus the cost of whatever part is leaking.

Related codes

P0455 Code: Evaporative Emission Control System Leak Detected (Large Leak)

P0456 Code: Evaporative Emission System Leak Detected (Very Small Leak)

P0440 Code: Evaporative Emission Control System Malfunction

P0442 by vehicle brand

Causes and repair costs for P0442 differ between makes. Pick your brand for the specifics.

P0442 on a Toyota

P0442 on a Honda

P0442 on a Ford

P0442 on a Chevy

P0442 on a Nissan

P0442 on a Mercedes-Benz

P0442 on a Volkswagen

P0442 on a Hyundai

P0442 on a Subaru

P0442 on a Mazda

P0442 on a Jeep

P0442 on a Lexus

P0442 on a Volvo

Related guide: How to Reset a Check Engine Light →

Updated 2026-08. This page is informational and not a substitute for professional diagnosis.