P0442 Evaporative Emission Control System Leak Detected (Small Leak)

P0442 indicates a small leak in the EVAP system. A small leak can be a loose cap, cracked hose, weak seal, valve leak, or another minor sealing fault.

Code details

Generic OBD-II · P0

System: Emissions
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume the smallest visible issue is the cause; small EVAP leaks often require a controlled smoke or pressure test.

Symptoms of P0442

Check-engine light, usually the only sign.
Occasionally a faint fuel-vapour smell.
No change in drivability.

Common causes of P0442

A loose, cracked, or missing fuel cap.
A small crack or poor seal in an EVAP hose.
A leaking purge or vent valve.
A seal fault at the fuel tank or charcoal canister.

Useful checks before replacing parts

Inspect the fuel cap seal and filler neck first if the vehicle has a removable cap.
Smoke-test the EVAP system when basic cap and hose checks do not identify the leak.
Check purge and vent valves for sealing, plus tank-top fittings and hoses that may be hard to see.

Related OBD-II codes

These nearby emissions entries can help compare wording and pin down the fault area.