how to diagnose P0420 code on Tesla Model S Plaid/Refresh (2021-present)

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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Inspect and Replace Faulty Sensors

• Sub-steps:
  1. Disconnect the vehicle's battery to prevent electrical shorts.
  2. Remove the upstream and downstream oxygen sensors using an O2 sensor socket.
  3. Inspect the connectors and wiring for damage; repair or replace as necessary.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer’s specifications (typically around 30-40 Nm).
  5. Reconnect the battery.

3. Address Catalytic Converter Issues

• Sub-steps:
  1. If the catalytic converter is suspected to be faulty, remove it from the exhaust system.
  2. Inspect for physical damage or clogging; if damaged, replace with a new catalytic converter.
  3. Ensure gaskets and seals are replaced to prevent leaks during reinstallation.
  4. Reinstall the catalytic converter and secure it according to the manufacturer's specifications.

4. Verify and Clear Codes

• Sub-steps:
  1. Use the OBD-II scanner to clear the P0420 code from the ECM.
  2. Start the vehicle and allow it to reach operating temperature.
  3. Recheck for any diagnostic trouble codes (DTCs) to confirm the issue is resolved.