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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack, jack stands, temperature probe.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Exhaust System

• Sub-steps:
  • Raise the vehicle using a jack and secure it with jack stands.
  • Visually inspect the entire exhaust system for any signs of leaks or damage, particularly around the catalytic converter.
  • If leaks are found, repair or replace the damaged sections of the exhaust.

3. Test and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Use a multimeter to test the voltage output of both sensors; they should vary between 0.1 to 0.9 volts.
  • If either sensor is faulty or showing constant values, replace them with new OEM sensors.
  • Reconnect the sensors and ensure they are securely fastened.

4. Replace Catalytic Converter (if testing shows failure)

• Sub-steps:
  • Remove the exhaust bolts securing the catalytic converter to the exhaust manifold and muffler.
  • Disconnect any oxygen sensors from the catalytic converter.
  • Carefully remove the old catalytic converter and install the new one, ensuring correct orientation.
  • Reconnect the oxygen sensors and secure all bolts to the manufacturer’s torque specifications (typically around 25-30 Nm).

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and allow it to reach operating temperature.