Evaporative emission system leak detected — small leak
The controller detected a small loss of vacuum, pressure, or sealing performance in the evaporative-emissions system during its leak test.
Conditions that can produce P0442
These are diagnostic branches, not a ranked parts list. Prevalence and testing order depend on the exact vehicle and failure scene.
- Loose, damaged, or incorrect cap/seal
- Small hose, fitting, canister, tank, or pump seal leak
- Purge or vent valve not sealing
- Leak-detection pump or pressure sensor problem
- Corrosion, debris, or temperature/fuel-level test issue
What to inspect next
- Stop for strong fuel odor or visible leakage
- Inspect cap and accessible vapor plumbing without creating sparks
- Use an approved low-pressure smoke/leak method
- Command or bench-test valves only with exact safe procedures
Evidence that strengthens the answer
Verify the repair
Preserve the pre-repair record, document exactly what changed, then repeat the relevant operating condition safely. Confirm no current or pending fault returns, review permanent-code and readiness state where applicable, and state which tests or modules remained unavailable.
This page explains a commonly standardized code at a general level. Confirm the exact definition, module, status, test conditions, thresholds, wiring, and service process for the vehicle application using current official information.