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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a flat surface, and apply the parking brake.
• Disconnect the battery to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, thread sealant.
• Sub-steps:
  1. Locate the pre-cat and post-cat oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust system.
  4. Apply thread sealant on the new sensors' threads.
  5. Install the new sensors and reconnect the electrical connectors.

3. Examine Catalytic Converter

• Tools Required: Jack stands, socket set, exhaust system cleaner.
• Sub-steps:
  1. Lift the vehicle and support it with jack stands.
  2. Inspect the catalytic converter for dents, rust, or other physical damage.
  3. If damaged, remove it using a socket set to unbolt the mounting points.
  4. Clean any exhaust residues from the exhaust pipe and mating surfaces.
  5. Install a new catalytic converter, ensuring proper alignment and secure it with bolts to specified torque values.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 fault code.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure no codes reappear.