P0430 — Catalyst System Efficiency Below Threshold (Bank 2)
Moderate severityWhat it means
The same fault as P0420 but on bank 2, the cylinder bank opposite cylinder 1 on V-type engines. The downstream oxygen sensor reports that the bank 2 catalytic converter is no longer cleaning the exhaust efficiently.
Common symptoms
- Usually only the check engine light
- Slightly reduced power or fuel economy
- Sulphur smell from the exhaust
- Failed emissions inspection
Likely causes
- Aged or failing bank 2 catalytic converter
- Faulty downstream oxygen sensor on bank 2
- Exhaust leaks near the sensor
- Misfires or fuel-mixture faults damaging the converter
- Oil or coolant burning
What to check first
- Resolve any other stored codes first
- Compare bank 2 upstream and downstream O2 signals in live data
- Inspect the bank 2 exhaust path for leaks
- Check fuel trims on both banks
Can you keep driving?
Generally drivable; plan a repair soon to avoid converter replacement costs growing and to pass emissions.
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