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

Solution

1. Preparation

• Gather tools and parts required for repair.
• Disconnect the vehicle’s battery to ensure safety before starting repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Use the O2 sensor socket to remove the upstream oxygen sensor.
  3. Inspect the sensor for carbon buildup or damage; replace if necessary.
  4. Repeat the process for the downstream oxygen sensor.
  5. Reconnect the new sensors and ensure they are properly tightened.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, torque wrench.
• Sub-steps:
  1. Raise the vehicle using a jack and secure with jack stands.
  2. Locate the catalytic converter and inspect for signs of damage or clogging.
  3. If damaged, disconnect the exhaust pipes connected to the catalytic converter.
  4. Remove the catalytic converter by unbolting it from the exhaust system.
  5. Install the new catalytic converter, ensuring proper alignment and torque specifications are followed.
  6. Reconnect the exhaust pipes and tighten all bolts.

4. Reset the Engine Control Unit (ECU)

• Tools Required: OBD-II scanner or battery disconnect tools.
• Sub-steps:
  1. Use the OBD-II scanner to clear the P0420 code from the ECU.
  2. Alternatively, disconnect the battery for about 10 minutes to reset the ECU.
  3. Reconnect the battery securely.