Ask Andy AIP0430 Catalyst System Efficiency Below Threshold (Bank 2)
What it means, what causes it, and what it costs to fix.
What P0430 means
Same as P0420, but for bank 2. That's the side of a V6 or V8 that doesn't have cylinder 1. The rear oxygen sensor on that bank is seeing exhaust that isn't being cleaned enough by the catalytic converter.
Can I drive with P0430?
Severity: Medium. Fix soon so it doesn't turn into something bigger.
Usually safe short term, but you'll fail emissions testing, and any misfire causing it will keep damaging the exhaust.
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Ask Andy about P0430Symptoms
- Check engine light
- Failed emissions test
- Sulfur smell from the exhaust
- Possible power loss if the converter is restricted
Common causes
Most likely first.
- Worn catalytic converter on bank 2
- Faulty bank 2 downstream oxygen sensor
- Exhaust leak on the bank 2 side
- Misfires or rich running on bank 2 cylinders
How to diagnose P0430
- Clear up any bank 2 misfire, lean, or rich codes first.
- Inspect the bank 2 exhaust manifold and pipes for leaks.
- Compare front vs. rear O2 activity in live data on bank 2.
- Check for TSBs and emissions-warranty coverage before buying a converter.
Tip: most US auto parts stores will read your codes for free.
Repair costs
| Bank 2 rear oxygen sensor | $150–$350 installed |
| Exhaust leak repair | $100–$400 |
| Catalytic converter | $600–$3,000+ installed |
Typical US prices. Your vehicle, region, and shop rates will change these.
P0430 FAQ
What does P0430 mean?
P0430 means "Catalyst System Efficiency Below Threshold (Bank 2)." Same as P0420, but for bank 2. That's the side of a V6 or V8 that doesn't have cylinder 1. The rear oxygen sensor on that bank is seeing exhaust that isn't being cleaned enough by the catalytic converter.
Can I drive with a P0430 code?
Usually safe short term, but you'll fail emissions testing, and any misfire causing it will keep damaging the exhaust.
What is the most common cause of P0430?
The most common cause is: Worn catalytic converter on bank 2. Other causes include faulty bank 2 downstream oxygen sensor and exhaust leak on the bank 2 side.
How much does it cost to fix P0430?
Typical repairs run about $100 to $3,000 in the US, depending on the cause. Bank 2 rear oxygen sensor: $150–$350 installed.
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