how to fix 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

• Tools Required: OBD-II scanner, multimeter, socket set, safety glasses, gloves.
• Disconnect the negative battery terminal to prevent electrical shocks.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Test 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 multimeter to test the resistance of each sensor; compare results to manufacturer specifications.
  4. If any sensor is outside spec, replace it.

3. Examine the Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for any dents, leaks, or signs of damage.
  2. Check for excessive carbon buildup on the converter; if present, clean it gently with a specialized cleaner.
  3. If the converter is damaged or clogged, remove it using a socket set and replace it with a new one.

4. Reassemble and Reconnect

• Sub-steps:
  1. Reconnect the oxygen sensors and ensure the connectors click into place securely.
  2. Reconnect the negative battery terminal.
  3. Start the vehicle and allow it to idle for a few minutes to ensure all systems are operational.

5. Final Checks

• After repairs, re-scan the vehicle with the OBD-II scanner to ensure the P0420 code is no longer present.