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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the sensors:
   • Use an oxygen sensor socket to unscrew the sensors from the exhaust manifold and catalytic converter.
   • Disconnect the electrical connectors carefully.
3. Install new sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and torque them to the manufacturer's specifications (typically around 30 lb-ft).
   • Reconnect electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:
   • Disconnect any exhaust brackets or hangers that may obstruct removal.
   • Use a socket set to unbolt the catalytic converter from the exhaust pipes.
2. Install new catalytic converter:
   • Clean the mating surfaces on the exhaust pipes to ensure a proper seal.
   • Position the new catalytic converter and secure it with bolts, torquing them to the specified value (usually around 30-40 lb-ft).
   • Reattach any brackets or hangers.

4. Clear the Error Code

1. Reset the OBD-II system:
   • Reconnect the negative battery terminal.
   • Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.

5. Final Checks

1. Start the engine: Allow it to reach operating temperature while monitoring for any leaks.
2. Test drive the vehicle: Ensure normal operation and monitor for the return of the check engine light.