OBD2 Codes

P0430 – Catalyst System Efficiency Below Threshold (Bank 2)

Catalytic converter efficiency is below threshold on bank 2.

Details

The downstream O2 sensor detects insufficient catalyst efficiency on bank 2. Usually caused by upstream problems.

Typical causesFailed catalytic converter upstream exhaust leak misfire history rich condition
SymptomsCheck engine light reduced performance possible failed emissions test
SeverityMedium — may fail emissions test
DIY checksCheck for exhaust leaks verify upstream O2 sensors check for misfire history
ToolsExhaust leak detector OBD2 scanner with live data

Utilities

Copy-paste helpers

Quick checklist

Check for exhaust leaks verify upstream O2 sensors check for misfire history

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P0420 – Catalyst System Efficiency Below Threshold (Bank 1)

Catalytic converter efficiency is below threshold; often caused by upstream issues.

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FAQ

Common questions

Is the catalytic converter definitely bad?

Not always—check for exhaust leaks and verify upstream sensors first.

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