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

P04EA

EVAP System Small Leak Detected Fuel Tank Side

The EVAP leak diagnostic has detected a small leak on the fuel tank side of the system - typically a hose, gasket, fuel cap, or fuel sender flange that does not seal completely. Vapor escapes during pressure or vacuum tests.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / EA

Possible causes

  • Fuel cap not sealing properly high
  • Vapor hose porous or cracked medium

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: 25–350 €
  • Estimated time: 0.3–2 h
  • Component: fuel tank
  • Component: fuel cap
  • Component: fuel sender seal
  • Component: evap hose tank side
  • MIL / check engine light
  • emissions-relevant

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