P0430 Toyota Highlander
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 Toyota Highlander 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 Toyota Highlander.
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 Toyota Highlander.
Common Causes on Toyota Highlander
- Bank 2 catalytic converter efficiency below threshold — degraded catalyst material
- Downstream O2 sensor reading similar waveform to upstream (catalyst not converting)
- Engine misfires damaging the catalytic converter over time
- Oil consumption past rings depositing phosphorus on catalyst substrate
Symptoms
- Check Engine Light on
- Failed emissions test
- Slight sulfur smell from exhaust
- No driveability symptoms in most cases — cat still functions partially
Notes for Toyota Highlander
Toyota catalytic converters are high-theft targets — consider installing a catalytic converter shield after replacement, especially on Tacoma, Tundra, and 4Runner.