P0430: Catalyst System Efficiency Below Threshold (Bank 2)

Common causes

• A worn or failing bank 2 catalytic converter
• A faulty bank 2 oxygen sensor
• An exhaust leak near the bank 2 sensors
• Misfires or a rich condition on that side of the engine

Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.

Symptoms

• Check engine light, often with no other symptoms
• A failed emissions test
• Sometimes reduced performance or a sulfur smell

Is it safe to drive?

Usually drivable short term, but find the root cause before it gets worse.

How to check it with a scanner

1. Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
2. Look for related codes (misfires, fuel trims, O2 sensors) and fix those first.
3. Compare bank 2 upstream and downstream O2 sensor readings in live data.
4. Check for exhaust leaks on the bank 2 side.
5. After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.

A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.

Questions

Related codes

• P0420: Catalytic converter efficiency, bank 1
• P0174: Engine running lean, bank 2
• P0300: Random or multiple cylinder misfire
• All trouble codes
• How to choose a car diagnostic scanner