OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P0442

Evaporative Emission System Leak Detected (Small Leak)

A small leak (typically equivalent to a 0.040 inch / 1.0 mm orifice) has been detected in the EVAP system. By far the most common cause is a fuel cap that is loose, missing, or has a worn seal.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 42

Possible causes

  • Fuel cap loose, missing, or worn seal high
  • Small crack in EVAP hose medium
  • Purge valve leaking low

Symptoms

  • Check engine light on
  • Possible smell of fuel near tank or engine bay
  • Failed emissions inspection
  • Loose-cap warning may appear

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 10–250 €
  • Estimated time: 0.1–2 h
  • Component: fuel filler cap
  • Component: evap canister
  • Component: evap purge valve
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication