how to fix P0420 code on Tesla Model 3 Original (2017-2023)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter.
• Remove the upstream (pre-catalytic) oxygen sensor.
  • Use an oxygen sensor socket for easier removal.
• Test the sensor resistance and voltage output according to manufacturer specifications.
• If faulty, replace the oxygen sensor.

3. Inspect the Catalytic Converter

• Tools Required: Socket set, torque wrench.
• Visually inspect the catalytic converter for any physical damage or signs of overheating.
• If it appears damaged or clogged:
  • Remove the catalytic converter by unbolting it from the exhaust system.
  • Ensure the exhaust pipes are free of obstructions and cracks.
  • Replace with a new catalytic converter, ensuring proper alignment.

4. Reassemble and Clear Codes

• Reinstall the oxygen sensors and any other removed components.
• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 trouble code from the system.

5. Test Drive

• Take the vehicle for a test drive to ensure the check engine light does not reappear and performance is restored.