how to fix P0420 code in Tesla Model S Plaid/Refresh (2021-present)

Learn how to diagnose and fix P0420 exhaust system issue in Tesla Model S Plaid. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, inspection mirror, safety goggles, work gloves.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream and downstream O2 sensors connected to the exhaust system.
2. Disconnect the Sensors: Carefully unplug the wiring harness from both sensors.
3. Remove the Sensors: Use the appropriate socket to unscrew and remove the sensors from the exhaust system.
4. Test the Sensors:
   • Use the multimeter to check the resistance of the sensors. Replace any sensors that are outside manufacturer's specified resistance range.
5. Install New Sensors: If replacement is necessary, install the new sensors, ensuring they are tightened to the manufacturer’s specified torque (typically around 30 lb-ft).
6. Reconnect the Wiring Harness: Plug the electrical connectors back into the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Visual Inspection: Examine the catalytic converter for signs of physical damage or blockage.
2. Check for Overheating: Use an infrared thermometer to measure the temperature of the inlet and outlet of the catalytic converter. A significant difference indicates issues.
3. Remove the Catalytic Converter: If replacement is needed, loosen the bolts securing the converter to the exhaust system using a socket set.
4. Install New Catalytic Converter: Position the new catalytic converter in place and secure it with bolts, tightening to the specified torque (around 40 lb-ft).
5. Reconnect any Electrical Components: If applicable, ensure all sensors and wiring are reconnected.

4. Final Steps

1. Reconnect the Battery: Reattach the negative battery terminal.
2. Clear the Error Code: Use the OBD-II scanner to clear the P0420 code.
3. Test Drive the Vehicle: Run the vehicle for a short distance to allow the engine control module to re-evaluate the exhaust system.