P0430 on Your 2023 Toyota Highlander
A P0430 trouble code on a 2023 Toyota Highlander signals that the engine control module has detected below-threshold catalytic converter efficiency on Bank 2. The 2023 Highlander is available with the 2.4L T24A turbocharged four-cylinder (replacing the previous 3.5L V6) or the 2.5L hybrid powertrain. On the turbo-four model, Bank 2 refers to the ECU's secondary catalyst monitor, while the designation is more straightforward on earlier V6 configurations.
On a vehicle this new, a worn catalytic converter is extremely unlikely. This code almost certainly points to a sensor issue, software calibration problem, or minor exhaust defect that should be covered under warranty.
Symptoms You May Notice
- Check engine light on the dashboard
- No significant performance changes
- Possibly a minor reduction in fuel economy
- Faint exhaust odor in rare cases
- Emissions test failure
Common Causes on the 2023 Highlander
- Defective Downstream O2 Sensor — A factory-defective oxygen sensor is the most likely cause on a new vehicle. It sends false catalyst efficiency data to the ECU.
- PCM Software Calibration Issue — The 2023 Highlander introduced a new engine option, and early calibration may need updates. Your dealer can check for TSBs.
- Exhaust Assembly Defect — A loose gasket, small gap, or improperly sealed connection from factory assembly can introduce air into the exhaust stream.
- Catalytic Converter Manufacturing Defect — Rare but possible. A converter with insufficient catalyst material from the factory.
Diagnosis Steps
Take it straight to the dealer. Your 2023 Highlander is under full factory warranty and the federal emissions warranty. Do not attempt repairs yourself or clear the code before the dealer visit. They need the stored code and freeze frame data for proper diagnosis using Toyota's Techstream system.
Repair Options and Costs
- Warranty Repair (First Choice) — Cost: $0. Everything exhaust-related is covered on a 2023 model.
- O2 Sensor (if out of warranty) — Parts: $70 to $185. Labor: $90 to $175. Total: $160 to $360.
- ECU Reflash — Free under warranty. $100 to $200 at a dealer out of warranty.
- Catalytic Converter (if out of warranty) — OEM: $850 to $1,700. Aftermarket: $400 to $750. Labor: $200 to $400.
Should You DIY?
No. On a 2023 model under warranty, let Toyota handle it at no cost. Any self-repair could complicate future warranty claims. The only thing worth doing at home is confirming the code with a personal OBD-II scanner.
Prevention Tips
- Follow Toyota's maintenance schedule
- Report check engine lights to your dealer promptly
- Use the recommended fuel grade for the new 2.4L turbo engine
- Keep all service records for warranty documentation
- Allow the engine to reach operating temperature before sustained highway driving