P0430 Subaru Outback
Catalyst System Efficiency Below Threshold (Bank 2) · Powertrain Code · Medium
What is P0430?
The catalytic converter on bank 2 is not operating efficiently. Same as P0420 but for the opposite bank.
When the Subaru Outback triggers code P0430 (catalyst system efficiency below threshold (bank 2)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Subaru Outback.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Subaru Outback.
Common Causes on Subaru Outback
- Deteriorated catalytic converter on Bank 2 (H6 engines or secondary converter)
- Failed rear O2 sensor giving false efficiency reading
- Misfire damage to the converter
- Exhaust leak near the converter
Symptoms
- Check Engine Light on
- Reduced power
- Sulfur smell from exhaust
- Failed emissions test
Notes for Subaru Outback
Subaru boxers run hotter on one bank; ensure the root cause is fixed before spending on a new catalytic converter.