P0430 on a Mazda: 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 Mazda

On a Mazda, P0430 tells you the bank 2 catalytic converter is cleaning exhaust below the level the computer expects. It mainly appears on Mazda V6 models such as the CX-9, since four-cylinder Mazdas only have one bank.

Is P0430 common on Mazdas?

P0430 is most often seen on higher-mileage CX-9 models, where the converter or a downstream oxygen sensor has worn out. Checking for exhaust leaks before replacing parts saves money on this fix.

Commonly reported on: CX-9, Mazda6, Tribute.

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	$60–200
Replace the bank 2 catalytic converter	Mechanic	$700–2500