P0430 on a BMW: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Drivable in the short term, but the bank 2 converter problem should be checked soon.

What P0430 means on a BMW

On a BMW, P0430 means the downstream oxygen sensor on bank 2 sees the catalytic converter cleaning exhaust less efficiently than it should. Because most BMWs use inline engines with only one bank, this code points mainly to V8 models, where each bank has its own converter.

Is P0430 common on BMWs?

P0430 is most common on BMW V8 models with higher mileage, such as the X5, X6, and 7 Series. On these cars, converter and oxygen sensor wear follows the same pattern as any V engine, and parts and labor cost more than on mainstream brands.

Commonly reported on: X5, X6, 5 Series, 7 Series.

Symptoms

Check engine light is on
Reduced fuel economy
Possible rotten-egg smell from the exhaust
Often no noticeable driving symptoms early on

Common causes

most common: Worn or failing catalytic converter on bank 2
common: Faulty downstream oxygen sensor on bank 2
common: Exhaust leak before or near the downstream sensor
less common: Unfixed misfire or rich fuel mixture that damaged the converter

How to fix it

Fix	DIY?	Typical cost
Inspect for exhaust leaks and repair them before replacing anything	Yes	$50–200
Test the downstream oxygen sensor and replace it if faulty	Yes	$80–250
Replace the bank 2 catalytic converter	Mechanic	$1200–3500