how to fix P0421 code in Tesla Model S Plaid/Refresh (2021-present)

Learn how to diagnose and fix P0421 exhaust system 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 negative battery terminal to ensure safety while working on the vehicle.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the O2 sensors from the exhaust system:
  • Locate the O2 sensors upstream and downstream of the catalytic converter.
  • Use an O2 sensor socket to unscrew them from their mounting points.
• Install new O2 sensors:
  • Apply anti-seize compound to the threads of the new O2 sensors (if specified by the manufacturer).
  • Screw in the new sensors and torque them to the manufacturer's specifications (typically around 30-40 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, torque wrench
• Raise the vehicle using a jack and secure it with jack stands.
• Detach the exhaust system:
  • Remove any bolts or clamps securing the exhaust system to the catalytic converter.
  • Carefully lower and remove the catalytic converter from the vehicle.
• Install a new catalytic converter:
  • Position the new catalytic converter and secure it with the original or new bolts.
  • Torque the bolts to the specified value (usually around 25-35 ft-lbs).
• Reattach the exhaust system and ensure all connections are tight.

4. Clear the Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0421 code from the ECM.