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.
Frequently asked questions
What is the most common cause of P0430?
The most likely cause is: Aged or failing bank 2 catalytic converter. Several other faults can set P0430 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0430 and keep driving?
Clearing P0430 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0430?
P0430 is a moderate-severity code. The car is often still drivable, but have it diagnosed soon — the underlying problem can get worse and it may fail an emissions test.
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