P0442 — EVAP system small leak detected

What this code generally means, its most common causes, and how serious it is.

TYPE: GENERICSYSTEM: CATALYST AND EMISSIONS

What does the code P0442 mean?

The EVAP system periodically tests itself by putting the tank under slight pressure or vacuum. This code appears when that test detects a small leak — smaller than the one that would trigger P0455 (a large leak).

Common possible causes

A gas cap that isn't fully tightened — the most common cause of a small leak.
A small crack in an EVAP hose — often invisible to the eye, found with a smoke test.
A worn or cracked cap seal — even with the cap properly tightened.

General severity

Generally minor — check the gas cap first

As with P0440, this is almost never a driving or safety issue. Check the gas cap first; if the code comes back despite a cap in good shape, a smaller leak in a hose becomes more likely.

This is still a general severity for this code, not a diagnostic for your car. Only a real read of your codes, with your mileage and vehicle history, can tell what's really going on.

Get a diagnostic for YOUR car

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Meca doesn't replace an in-person check by a professional. For any serious sign (a flashing light, a major loss of power, a fuel smell), see a mechanic promptly.

Frequently asked questions

Is this worse than a P0455?

No, it's the opposite: P0442 indicates a smaller leak than P0455. Both are generally not a driving risk.

How do you find a leak this small?

A smoke test (non-toxic smoke injected into the system under slight pressure) is the most reliable way to spot a small crack — hard to do without the right equipment.

Should I be worried about safety?

No, a small EVAP leak isn't a safety issue. It's mostly a fuel-vapor emissions concern.