P0430: Catalyst System Efficiency Below Threshold (Bank 2)
Severity: low
What it means: The bank 2 catalytic converter isn't cleaning the exhaust as well as it should, judged by comparing the O2 sensors before and after it.
Safe to drive? Usually safe to drive in the short term, but it will fail an emissions test. If the car has power loss or a rotten-egg smell, or you also have misfire codes, have it checked right away.
Common symptoms
- Check-engine light
- Often no drivability change
- Failed emissions test
- Sometimes a sulfur smell or sluggishness
Likely causes, ranked
- Worn-out catalytic converter$1,348Shop
CarMD 2024 national average about $1,348
- Faulty or slow downstream/upstream O2 sensor$254DIY
CarMD 2024 national average about $254
- Exhaust leak near the O2 sensorsShop
- Misfires or a rich mixture that damaged the converterShop
Vehicle-specific notes
- 2011–2014 Ford F-150: 3.5L EcoBoost: misfire or stumble on hard acceleration after highway driving in humid weather. Ford's bulletin adds a revised deflector and PCM update, and checks the left catalytic converter if P0430 is set. Read the full answer · Source
What it means: The bank 2 catalytic converter isn't cleaning the exhaust as well as it should, judged by comparing the O2 sensors before and after it.
Severity: Low. Safe to drive? Usually safe to drive in the short term, but it will fail an emissions test. If the car has power loss or a rotten-egg smell, or you also have misfire codes, have it checked right away.
DIY or shop?
Fix any misfire or fuel codes first. O2 sensors can be a DIY job, but get a shop diagnosis before buying a converter.
Before you replace parts
- Read all stored codes and freeze-frame data. Fix misfire, fuel or sensor codes before chasing emissions codes.
- Check the simple things first: connectors, vacuum hoses, fluid levels and the gas cap.
- Clear the code only after a repair, then confirm it stays off after a few drives.
- Check your VIN for recalls and service bulletins.
Safety / mechanic note
Generally not urgent, but a code only points to a system, not always a specific part. Verify with a mechanic before buying expensive parts.