how to fix P0420 catalyst efficiency issue on Tesla Model S Plaid/Refresh (2021-present)

Learn how to diagnose and fix P0420 catalyst 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.
• Disconnect the negative terminal of the battery to avoid electrical issues.
• Allow the exhaust system to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Unplug the connectors from each sensor.
  3. Use an O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors by threading them into place and tightening to manufacturer specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors to the sensors.

3. Evaluate and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove the exhaust system components that obstruct access to the catalytic converter.
  2. Visually inspect the catalytic converter for signs of damage or blockage (e.g., rattling noise, discoloration).
  3. If replacement is necessary, detach the catalytic converter from the exhaust pipes (may require cutting or unbolting).
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Reassemble the exhaust system and ensure all connections are secure.

4. Clear Error Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 error code and reset the check engine light.