how to diagnose a P0420 code in my Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, infrared thermometer.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust pipes.
  4. Install the new sensors by threading them into the exhaust and tightening them to the manufacturer’s specifications (typically 30 lb-ft).
  5. Reconnect the electrical connectors to each sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove any heat shields or mounting brackets securing the catalytic converter.
  2. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  3. Carefully remove the catalytic converter from the vehicle.
  4. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  5. Reattach the exhaust pipes, tightening to the manufacturer’s specifications (typically 25 lb-ft).
  6. Reinstall any heat shields or brackets that were removed.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the vehicle battery.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive under various conditions (city, highway) to ensure the issue is resolved.