how to fix P0420 error code in Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, exhaust pressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical short circuits.

2. Inspect and Replace Oxygen Sensors

• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Detach the electrical connectors from both oxygen sensors.
• Use a socket wrench to remove the old sensors.
• Apply anti-seize compound to the threads of the new sensors.
• Install the new upstream and downstream oxygen sensors, tightening them to the manufacturer’s specifications (typically around 30 Nm).
• Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

• If the catalytic converter is found to be damaged or clogged, it will need to be replaced.
• Use the socket set to unbolt the catalytic converter from the exhaust system.
• Carefully remove the old catalytic converter, ensuring no debris falls into the exhaust system.
• Install the new catalytic converter, ensuring proper alignment and sealing.
• Torque the bolts to the manufacturer’s specifications (typically around 40-50 Nm).

4. Final Checks

• Reconnect the negative battery terminal.
• Start the engine and let it run for a few minutes to check for leaks and ensure everything is functioning correctly.