Symptoms of P0430
- Check-engine light, usually with no change in how the car drives.
- A failed emissions test.
- Sometimes a faint sulphur / rotten-egg smell.
- Rarely, a rattle from inside the converter.
Common causes of P0430
- A worn or failed catalytic converter on bank 2.
- A lazy or failed downstream oxygen sensor.
- An exhaust leak upstream of the converter.
- An underlying misfire or fuel-trim fault that damaged the cat.
Useful checks before replacing parts
- Inspect bank 2 exhaust leaks, downstream and upstream sensor data, wiring faults, and catalyst-monitor readiness conditions.
- Review misfire history, fuel trims, oil consumption, coolant contamination, and rich or lean operation that can damage the catalyst.
- Compare bank 1 and bank 2 sensor patterns when both banks are available to spot sensor or engine-control differences.
Related OBD-II codes
These nearby emissions entries can help compare wording and pin down the fault area.