how to fix P0420 error code in my Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to prevent electrical issues during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Unplug the electrical connectors from the sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new sensors by reversing the removal steps and ensure they are tightened to the manufacturer's torque specifications (typically around 30 ft-lbs).

3. Examine and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench
• Sub-steps:
  1. Remove the exhaust heat shield if applicable.
  2. Disconnect the exhaust pipes from the catalytic converter using the socket set.
  3. Remove any mounting bolts securing the catalytic converter.
  4. Inspect the catalytic converter for any signs of physical damage or clogging.
  5. If defective, install the new catalytic converter by reversing the removal process and torque the bolts to manufacturer specifications.
  6. Reinstall the heat shield if it was removed.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Reconnect the vehicle battery.
  2. Use the OBD-II scanner to clear the P0420 error code from the system.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Perform a test drive to ensure the Check Engine light does not re-illuminate.