P0430 Code: Catalyst System Efficiency Below Threshold (Bank 2)
P0430 means the catalytic converter on bank 2 isn’t cleaning the exhaust efficiently — the same fault as P0420 but on the other bank.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $200 – $2,200
- Time to fix
- 1-3 hours
What it means
Common causes are an aged catalytic converter, a failing downstream O2 sensor, or an exhaust leak on bank 2. This is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer OBD-II vehicle — cars, trucks, and modern fuel-injected motorcycles — from any manufacturer (Toyota, Honda, Ford and the rest). Read it with any OBD-II scanner; the meaning is the same across brands, though the exact repair can vary by engine.
Symptoms
- Check engine light on
- Slight economy drop; possible smell
- Failed emissions test
How to fix it
- 1
Check O2 sensors and exhaust
1. Compare upstream/downstream O2 data on bank 2. 2. Replace a lazy sensor or fix leaks first. 3. Replace the converter only if genuinely failed, then clear the code.
Frequently asked questions
What’s the difference between P0420 and P0430?
Same fault (catalyst efficiency) — P0420 is bank 1, P0430 is bank 2. Only V-type/flat engines with two banks get P0430.
Last updated July 16, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.