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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

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. Using an O2 sensor socket, remove the sensors from their positions.
  4. Install new oxygen sensors, ensuring proper torque (typically 30-40 ft-lbs) and reconnect the electrical connectors.

3. Inspect the Catalytic Converter

• Sub-steps:
  1. Visually inspect the catalytic converter for signs of damage or blockage.
  2. If the converter is damaged or clogged, loosen the clamps or bolts securing it to the exhaust system.
  3. Remove the catalytic converter and replace it with a new unit, ensuring proper alignment and tightness of the bolts (consult manufacturer specifications for torque values).

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the vehicle and perform a test drive to ensure the issue is resolved.