P0430
Catalyst System Efficiency Below Threshold (Bank 2)
The Bank 2 catalytic converter is not operating efficiently.
Same as P0420 but for Bank 2. If both P0420 and P0430 are present, both converters are failing, which often indicates a systemic issue such as engine running rich, chronic misfires, or age-related degradation.
Symptoms
Common Causes
Worn catalytic converter
HIGHCatalyst material has degraded.
Previous misfire damage
MEDIUMMisfires sent unburned fuel into the converter.
Faulty Bank 2 downstream O2 sensor
LOWSensor incorrectly reporting converter failure.
Step-by-Step Diagnosis
Compare O2 signals
mediumMonitor Bank 2 upstream vs downstream O2 sensor activity.
Fix underlying issues
easyAddress any misfire, lean, or rich codes before replacing the converter.
Replace Bank 2 converter
hardIf confirmed bad, replace the Bank 2 catalytic converter.
Commonly Seen With
P0430 is frequently found alongside these codes:
Related Codes
Frequently Asked Questions
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