how to fix P0420 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.
• Raise the vehicle using jack stands for better access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the pre-catalytic converter oxygen sensor:
  • Disconnect the electrical connector.
  • Use the O2 sensor socket to unscrew the sensor.
• Install the new O2 sensor:
  • Apply anti-seize compound to the threads.
  • Torque to manufacturer specification (usually around 30 lb-ft).
• Repeat for the post-catalytic converter sensor if necessary.

3. Examine and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger tool.
• Detach the catalytic converter from the exhaust system:
  • Remove the bolts connecting the converter to the exhaust pipe and manifold.
  • Use the exhaust hanger tool to remove any hangers supporting the converter.
• Install the new catalytic converter:
  • Position the new converter and secure it with bolts, torquing to manufacturer specifications.
  • Reattach hangers and ensure everything is aligned properly.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code.