OBD-II code guide
P0430 Catalyst System Efficiency Below Threshold Bank 2
P0430 means the catalytic converter monitor for bank 2 is below the expected efficiency threshold.
What it means
The downstream oxygen sensor pattern suggests the bank 2 converter is not storing oxygen properly.
Common symptoms
- Check engine light
- Failed emissions test
- Possible exhaust rattle
- Usually normal driving feel
- Reduced power if restricted
Likely causes
- Aging catalytic converter
- Exhaust leak
- Misfire damage
- Oxygen sensor issue
- Rich or lean running condition
First checks
- Fix misfire and fuel trim codes first.
- Inspect for exhaust leaks.
- Compare upstream and downstream sensor activity.
- Confirm bank 2 location before replacing parts.