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

• Gather necessary tools and parts.
• Disconnect the vehicle's 12V battery to ensure safety.
• Allow the vehicle to cool down completely before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter.
• Remove the upstream and downstream oxygen sensors:
  1. Use the O2 sensor socket to unscrew the sensors from their respective locations.
  2. Inspect the sensors for damage or excessive carbon buildup.
• Replace any faulty oxygen sensors with OEM parts:
  1. Apply anti-seize compound to the threads of the new sensors.
  2. Install the upstream sensor first, then the downstream sensor, tightening to manufacturer specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust hanger removal tool.
• If the catalytic converter is determined to be faulty:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Remove exhaust hangers using the exhaust hanger tool to free the exhaust system.
  3. Unbolt the catalytic converter from the exhaust pipes using a socket set.
  4. Install the new catalytic converter:
     • Align it properly and secure it with bolts to manufacturer torque specifications (typically around 40 lb-ft).

4. Reconnect Components

• Reconnect the oxygen sensors to their respective connectors.
• Reconnect the vehicle's 12V battery.