P0442 – EVAP system – small leak detected

P0442 means the evaporative-emissions monitor detected a small leak. The deviation may not be visible or noticeable by smell from outside the vehicle.

Powertrain · Evaporative emissions (EVAP)

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Meaning and affected system

The EVAP test assesses sealing under particular enabling conditions. It does not necessarily run immediately after starting. A code that does not return straight after clearing is therefore not proof of a successful repair.

Possible causes

A compromised sealing surface at a fitted fuel cap is one possibility.
Small leaks at connections, vapour lines or valves are others.
The particular EVAP design determines the areas that need testing.

Possible symptoms

The check engine light may be the only sign.
P0442 does not establish a particular running symptom or a detectable fuel smell.

Useful diagnostic considerations

Have the fuel-cap seal and accessible connections inspected to the vehicle specification.
For a recurring finding, arrange suitable leak detection rather than replacing several components speculatively.
After corrective work, distinguish a successful monitor result from a test that has not yet run.

What this code does not prove

Small describes a monitoring result, not the safety significance of a fuel leak. Actual fuel escaping or a strong fuel smell requires the relevant vehicle and roadside instructions regardless of the code.

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Sources and interpretation

This explanation was editorially cross-checked against the technical sources below. Manufacturer documents concern particular vehicle applications; their thresholds and repair procedures must not be applied universally.

OBD-II code data: OBDex (CC0 1.0) · 196fddffb6ef

Editorial source review: 16 October 2026.

The causes listed are possibilities without a likelihood ranking. This page cannot replace diagnosis of the vehicle. A code alone confirms neither a failed component nor that continuing to drive is safe. The actual condition, warnings, handbook and applicable manufacturer diagnostics determine the next step.