how to fix P0420 code on my Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, thermal camera/infrared thermometer, safety glasses, gloves.
• Safety Warnings: Disconnect the battery before starting any electrical work. Allow the exhaust system to cool before inspecting.

2. Inspect and Replace Oxygen Sensors

• Remove the oxygen sensor connector from the upstream (pre-catalytic converter) and downstream (post-catalytic converter) sensors.
• Use a socket to carefully unscrew the oxygen sensors from their locations.
• Install the new oxygen sensors, ensuring they are properly torqued (typically around 30-40 ft-lbs, but check specifications).
• Reconnect the sensor connectors securely.

3. Check and Replace Catalytic Converter (if necessary)

• If the catalytic converter is confirmed to be faulty:
  • Disconnect the exhaust system from the catalytic converter. This may involve removing bolts or clamps.
  • Remove the catalytic converter from its mounting location.
  • Install the new catalytic converter, ensuring proper alignment and securing it with bolts or clamps. Torque to manufacturer specifications.

4. Clear Codes and Test

• Reconnect the battery and use the OBD-II scanner to clear any existing codes.
• Start the vehicle and allow it to reach operating temperature.
• Take the vehicle for a test drive to monitor if the Check Engine Light returns.