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

P0430

Catalyst System Efficiency Below Threshold (Bank 2)

Same condition as P0420 but on bank 2. On engines with one shared catalyst per bank, P0420 and P0430 appearing together usually point to age rather than damage.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 30

Possible causes

  • Catalyst aged or contaminated high
  • Downstream oxygen sensor drift medium

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: 600–2500 €
  • Estimated time: 1.5–5 h
  • Component: catalytic converter
  • Component: oxygen sensor upstream
  • Component: oxygen sensor downstream
  • 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