The most common causes are: Worn or failed Bank 2 catalytic converter; Aging downstream (Bank 2, Sensor 2) oxygen sensor; Exhaust leak on the Bank 2 side; Misfire or fuel trim problem on Bank 2 that has damaged the converter; Aftermarket converter not meeting factory efficiency thresholds.

How much does it cost to fix P0430?

Typical repairs range from $50–$250 for repair bank 2 exhaust leak up to $400–$1,500 for replace bank 2 catalytic converter. Costs vary by vehicle and region.

P0430powertrain

P0430 – Catalyst System Efficiency Below Threshold (Bank 2)

What does P0430 mean?

P0430 is the Bank 2 equivalent of P0420: the catalytic converter on the bank that does not contain cylinder #1 is operating below its efficiency threshold. It only appears on V6, V8, and other multi-bank engines — inline engines have just one bank and cannot set this code.

What causes P0430?

Listed from most to least common:

1Worn or failed Bank 2 catalytic converter
2Aging downstream (Bank 2, Sensor 2) oxygen sensor
3Exhaust leak on the Bank 2 side
4Misfire or fuel trim problem on Bank 2 that has damaged the converter
5Aftermarket converter not meeting factory efficiency thresholds

Code breakdown

SystemP — Powertrain

TypeGeneric (standardized SAE / OBD-II code — same meaning across most manufacturers)

SubsystemAuxiliary emission controls

Common symptoms

Check engine light on with normal drivability
Failed emissions test
Possible mild fuel economy loss

How to diagnose

1Confirm which side is Bank 2 for your specific engine — it varies by manufacturer and getting this wrong wastes money.
2Fix any misfire or fuel trim codes before diagnosing P0430.
3Graph Bank 2 upstream vs downstream O2 sensor activity with live data.
4Inspect the Bank 2 exhaust path for leaks.
5If P0420 and P0430 appear together, suspect a shared root cause such as a fuel delivery problem rather than two failed converters.

Same as P0420 — drivability is usually unaffected, but the vehicle will fail emissions testing.

Common fixes and estimated costs

Repair	Estimated cost
Repair Bank 2 exhaust leak	$50–$250
Replace Bank 2 downstream O2 sensor	$120–$350
Replace Bank 2 catalytic converter	$400–$1,500

Costs are rough US estimates including parts and labor. Actual pricing varies significantly by vehicle, region, and shop rates.

Good to know

When P0420 and P0430 set at the same time, it is unlikely both converters failed simultaneously. Look for a common cause upstream — fuel pressure, a failing MAF sensor, or an intake leak.

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This information is provided for general reference only and may vary by manufacturer, model, and year. It is not a substitute for professional diagnosis or repair.