Trouble codes › P0430

P0430 Catalyst System Efficiency Below Threshold (Bank 2)

Emissions

P0430 means the catalytic converter on bank 2 isn't cleaning the exhaust well enough, usually a worn converter, an exhaust leak or a lazy oxygen sensor.

The same check as P0420, on the other side of a V6 or V8 engine (bank 2, the side without cylinder 1). The engine computer sees that the oxygen sensor after the bank 2 catalytic converter is reading almost the same as the one before it, which means the converter isn't storing and cleaning the exhaust well enough.

Can I keep driving? Yes, for now.

Usually safe to drive for now, but it will fail an emissions test. Fix any misfire first: unburned fuel overheats and ruins converters.

Common causes

  1. A worn-out bank 2 catalytic converter
  2. An exhaust leak near the bank 2 oxygen sensors
  3. A failing bank 2 rear (downstream) oxygen sensor
  4. Misfires, oil burning or a rich condition on bank 2 damaging the converter

Symptoms

  • Check-engine light, usually with no change in how it drives
  • Failed emissions test
  • Sometimes a rattle, rotten-egg smell or loss of power

What to check first

  1. Scan for other codes; fix misfires (P0300-P0308) and fuel trim codes first.
  2. Check for exhaust leaks on bank 2, from the manifold to the rear oxygen sensor.
  3. Compare the bank 2 front and rear oxygen sensor readings with a scan tool: a rear sensor that switches like the front points to the converter.
  4. If you have both P0420 and P0430, look for a cause that affects both banks (oil or coolant burning, misfires, a fuel problem) before replacing two converters.
  5. Check for service bulletins and the emissions warranty on your converter.

What does P0430 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0430

No scanner? Most auto parts stores read check-engine codes for free.

Related codes

General guidance for P0430 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.