P0430 on Infiniti: How to Diagnose & Fix
Catalyst System Efficiency Below Threshold (Bank 2)
1 Infiniti model · 1 documented issue · $600-$3,500 repair
P0430 on Infiniti by model: symptoms, diagnosis and fix
First-generation FX35s commonly set P0420 and/or P0430 (catalyst efficiency below threshold, bank 1/bank 2) as the two close-coupled converters degrade, often between 80,000 and 130,000 miles. Contributing causes on this engine are oil consumption coating the catalyst and rich running from failed coils/plugs or sensor faults. Dealers quote about $1,500 per converter plus labor, with the OEM manifold-integrated cats being the expensive part. Aftermarket high-flow cats compatible with the G35/350Z are a common lower-cost route, and replacing downstream O2 sensors alone often does not clear the code.
Common Symptoms
- Check engine light with P0420 and/or P0430
- Failed emissions inspection
- Sulfur / rotten egg smell from exhaust
- Reduced power or rattle from the converter when substrate breaks up
How to Fix
Confirm the code is genuine catalyst degradation: check for misfires, oil consumption, rich fuel trims and exhaust leaks near the rear O2 sensors first, and replace failed coils/plugs before buying converters. Then replace the affected converter(s); OEM runs $1,500-2,000 installed per side, aftermarket CARB-compliant units $300-550 each plus labor. Fix the upstream cause (oil consumption, misfire) or the new cats will fail again.
Sources for this issue (3)
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 Infiniti?
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 Infiniti it is documented across 1 model: FX35.
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 Infiniti?
Published repair estimates on Infiniti range from $600 to $3,500 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.