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 vehicle's battery to prevent electrical issues.
• Ensure the vehicle is on a flat surface and secured with wheel chocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Spray penetrating oil on the O2 sensors to ease removal.
• Disconnect the electrical connectors from the upstream and downstream O2 sensors.
• Use the O2 sensor socket to remove the sensors from the exhaust system.
• Install new O2 sensors and torque them to the manufacturer’s specifications (typically around 30 lb-ft).
• Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust gasket
• Remove the bolts securing the catalytic converter to the exhaust system using a socket set.
• Carefully lower the catalytic converter from the vehicle.
• Inspect the old catalytic converter for any signs of damage or blockage.
• Replace with a new catalytic converter and ensure a proper fit with an exhaust gasket.
• Torque the bolts to the manufacturer’s specifications (typically around 25-30 lb-ft).

4. Clear Codes and Test

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0421 code.
• Start the vehicle and allow it to reach normal operating temperature.
• Monitor for any reoccurrence of the P0421 code.