P0430 — Catalyst System Efficiency Below Threshold (Bank 2)

What it means

Identical in meaning to P0420 but for bank 2 — the cylinder bank that does not contain cylinder number one, so the code only appears on V-type and boxer engines with two separate exhaust paths. The downstream oxygen sensor of that bank has started to mirror the upstream sensor, meaning the converter no longer stores enough oxygen. If P0420 and P0430 appear together, the cause is more often a shared upstream problem (mixture, misfires, oil consumption) than two simultaneously dead converters.

Likely causes (most common first)

1. Worn-out catalytic converter on bank 2
2. Lazy or contaminated downstream oxygen sensor on that bank
3. Exhaust leak between the manifold and the rear sensor of bank 2
4. Long-term rich mixture, misfires or leaking injectors on the cylinders of that bank
5. Oil or coolant consumption poisoning the substrate
6. Wiring fault or swapped connectors between the two banks after service work

Can you drive with it?

Driving is possible, but plan the repair — emissions are high and the converter keeps degrading.