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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Safety gear: gloves and safety glasses.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

• 2.1 Disconnect the negative terminal of the battery to prevent electrical shorts.
• 2.2 Locate the upstream and downstream oxygen sensors. They are typically found in the exhaust system before and after the catalytic converter.
• 2.3 Use an O2 sensor socket to remove the faulty oxygen sensor(s).
• 2.4 Install the new oxygen sensor(s) by screwing them in place and tightening them to the manufacturer’s specified torque (usually around 30 lb-ft).
• 2.5 Reconnect the battery terminal.

3. Inspect and Replace Catalytic Converter (if necessary)

• 3.1 If oxygen sensors are functioning properly, inspect the catalytic converter for physical damage or blockage.
• 3.2 If replacement is needed, remove the exhaust pipe sections connected to the catalytic converter using a socket set.
• 3.3 Install the new catalytic converter, ensuring all gaskets are replaced and connections are secure.
• 3.4 Reassemble the exhaust system and tighten all bolts to the specified torque.

4. Recheck System

• 4.1 Start the vehicle and allow it to reach operating temperature.
• 4.2 Use the OBD-II scanner to clear the P0420 code and monitor for any reoccurrence.
• 4.3 Test drive the vehicle under various conditions to ensure the engine operates smoothly and the check engine light does not return.