P0430
Catalyst System Efficiency Below Threshold (Bank 2)
OBD-II
Catalytic converter
What it means
Bank 2 catalytic converter underperforming. Same rule as P0420: verify the downstream O2 sensor and check for exhaust leaks first.
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P0420
Catalyst System Efficiency Below Threshold (Bank 1)
Catalytic converterMedium
P0421
Warm Up Catalyst Efficiency Below Threshold (Bank 1)
Catalytic converterMedium
P0422
Main Catalyst Efficiency Below Threshold (Bank 1)
Catalytic converterMedium
P0431
Warm Up Catalyst Efficiency Below Threshold (Bank 2)
Catalytic converterMedium
P0432
Main Catalyst Efficiency Below Threshold (Bank 2)
Catalytic converterMedium
General reference only — what a code means can vary by make and model. Confirm with a qualified technician.