P0430 on Porsche: How to Diagnose & Fix
Catalyst System Efficiency Below Threshold (Bank 2)
1 Porsche model · 1 documented issue · $2,000-$6,000 repair
P0430 on Porsche by model: symptoms, diagnosis and fix
The catalytic converters on 958-generation Cayennes fail prematurely due to substrate breakdown and thermal degradation. The V8 models with four cats are especially expensive to repair. Failed converters trigger check engine lights and cause the vehicle to fail emissions testing.
Common Symptoms
- Check engine light with P0420/P0430 codes
- Sulfur/rotten egg smell from exhaust
- Reduced power and sluggish acceleration
- Failed emissions test
- Rattling from underneath vehicle
How to Fix
Replace the failed catalytic converter(s). OEM converters are extremely expensive ($2,000-$4,000 each). Aftermarket CARB-compliant converters are available at lower cost. Diagnose the root cause of failure (oil burning, misfires) before replacing to prevent recurrence.
Owner tips & cautions
- WarningBefore replacing catalytic converters, fix any oil consumption or misfire issues first — these are the most common root causes of premature cat failure and will destroy the new converters as well.
P0430 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0430 mean on a Porsche?
P0430 stands for "Catalyst System Efficiency Below Threshold (Bank 2)." This code means the catalytic converter on Bank 2 (the side of the engine that does not contain cylinder #1) is not reducing emissions as effectively as it should. The computer compares the readings of the oxygen sensors before and after the converter; if the downstream sensor's signal starts mirroring the upstream one, it indicates the converter is no longer storing and processing oxygen properly. This usually points to a worn-out or damaged catalytic converter, but it can also be caused by faulty sensors or upstream engine problems that have poisoned the converter. The car will generally still run, but it will fail an emissions test. On Porsche it is documented across 1 model: Cayenne.
What are the most common causes of P0430?
The most common causes of P0430 are: Worn-out or failed catalytic converter (Bank 2), Faulty downstream (post-cat) oxygen sensor, Faulty upstream oxygen sensor giving bad data, Exhaust leak near the converter or sensors, Engine misfire or oil/coolant burning that damaged the catalyst, Running too rich or too lean over time, Aftermarket or non-compliant catalytic converter. The specific cause varies by vehicle.
How much does it cost to fix P0430 on a Porsche?
Published repair estimates on Porsche range from $2,000 to $6,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0430 on a different make?
View P0430 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.