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OBD-II FAULT CODE

P0442: Evaporative emission system leak detected (small leak)

Evaporative emissionsGeneric powertrain

The evaporative-emissions monitor has detected a leak consistent with its small-leak threshold. The test logic and threshold depend on the vehicle.

Possible causes

Examples to investigate; this list is not a probability ranking or a diagnosis.

  • Fuel-cap or filler-seal leak where fitted
  • Cracked EVAP hose or connection
  • Purge or vent valve not sealing

Symptoms you might notice

  • Check-engine light
  • Often no drivability symptom; fuel odour may be present

Diagnostic approach

  1. Inspect the fuel filler and cap seal if the vehicle uses a cap.
  2. Inspect accessible vapour lines and connections.
  3. Have the EVAP system tested with manufacturer-approved low-pressure equipment; avoid ignition sources.

Save codes and freeze-frame information before clearing anything. A cleared warning light does not prove that a repair worked; the applicable monitor must run again.

Possible repairs — after testing

  • Replace damaged seals or hoses when a leak is confirmed.
  • Repair a purge or vent fault verified by testing.

Related codes

This is general diagnostic orientation, not a manufacturer-specific repair procedure. A qualified technician can confirm test conditions and safe working methods.