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OBD-II · Engine and powertrain (P)

P0442

EVAP system small leak detected

What it means

The evaporative emission system cannot hold pressure or vacuum: there is a small leak. Only cars with a leak-detection pump or tank pressure sensor run this test; many European-market cars do not.

Symptoms

  • engine warning light
  • sometimes a faint fuel smell
  • no change in how the car drives

Likely causes, most likely first

Likely causes, most likely first
No.Cause
01worn fuel cap seal
02cracked EVAP hose
03leaking charcoal canister
04leaking purge valve
05faulty leak-detection pump

What to check, step by step

  1. 01Check the fuel cap: seal present, undamaged and tightened until it clicks
  2. 02Inspect the EVAP hoses, canister and filler neck for cracks and loose connections
  3. 03Smoke-test the EVAP system to find the leak
  4. 04Check the leak-detection pump or tank pressure sensor and the canister vent