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

P2424

HC Adsorption Catalyst Efficiency Below Threshold Bank 2

The hydrocarbon adsorption catalyst on bank 2 - which traps HC during cold-start until the main catalyst lights off - is degraded; HC slip during cold start is above the calibrated threshold.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / 24

Possible causes

  • Catalyst adsorber aged high

Symptoms

  • Check engine light on
  • Failed emissions inspection
  • Possibly slightly increased fuel consumption
  • Sulfur (rotten egg) smell from exhaust under load

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 400–1800 €
  • Estimated time: 1.5–5 h
  • Component: hc adsorption catalyst b2
  • 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