how to fix the P0420 code in my Toyota Highlander Fourth Generation (2020-present)?

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the battery to ensure safety.
• Allow the engine to cool down if it has been running.

2. Inspect and Clean Components

• Tools Required: Socket set, wire brush, cleaning solvent
• Remove any debris or soot from the catalytic converter entrance and exit areas with a wire brush.
• Clean or replace any damaged heat shields that may affect exhaust flow.

3. Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• Remove the upstream (pre-catalytic converter) oxygen sensor using the O2 sensor socket.
• Install the new upstream oxygen sensor and torque to manufacturer specifications (usually around 30-40 ft-lbs).
• Repeat for the downstream (post-catalytic converter) oxygen sensor if necessary.

4. Replace Catalytic Converter (if required)

• Tools Required: Socket set, cutting tool (if necessary)
• Disconnect exhaust pipes from the catalytic converter by removing the bolts or cutting the pipe if rusted.
• Remove the old catalytic converter and install the new one, ensuring proper alignment.
• Securely fasten all connections and torque to manufacturer specifications.

5. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.