my Tesla Model S Plaid/Refresh (2021-present) engine light keeps coming on for P0420

Learn how to diagnose and fix P0420 exhaust system issue in Tesla Model S Plaid. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, infrared thermometer.
• Safely park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Remove the connectors of both oxygen sensors.
  3. Using a socket, unscrew and remove the oxygen sensors from their mounts.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer's specifications.
  5. Reconnect the sensors and ensure all connections are secure.

3. Inspect and Test Catalytic Converter

• Sub-steps:
  1. If the oxygen sensors were not the issue, visually inspect the catalytic converter for any signs of damage or excessive carbon buildup.
  2. Use the infrared thermometer to measure the temperature difference between the inlet and outlet of the catalytic converter (should typically be a difference of 100-200°F).
  3. If the temperature difference is inadequate, consider replacing the catalytic converter.

4. Clear Error Codes

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear any stored trouble codes.
  3. Perform a road test to monitor the vehicle's performance and check if the check engine light returns.