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Powertrain fault code

P0430: Catalyst System Efficiency Below Threshold (Bank 2)

Monitor

Usually drivable. Fix any misfires first: they are often what kills the converter.

What P0430 means

The catalytic converter is not cleaning the exhaust as well as it should, judged by comparing the oxygen sensors before and after it.

Common causes

  • Worn catalytic converter
  • Faulty rear O2 sensor
  • Exhaust leak
  • Earlier misfires that damaged the converter

What to check first

  1. Check for exhaust leaks.
  2. Fix any misfire or fuel trim codes first.
  3. Have the rear O2 sensor checked before replacing the converter.

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Read your car's codes yourself, free

Plug a cheap ELM327 OBD-II adapter into the port under the dashboard and open the scan tool: Chrome or Edge on a computer with a USB adapter, or Chrome on Android with a Bluetooth LE adapter. It reads and clears codes and shows emissions readiness. It does not work on iPhone.

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Related codes

P0420

General guidance only, not a diagnosis. A qualified mechanic should confirm the cause before you replace parts.