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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery to prevent electrical issues during the repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Remove the upstream oxygen sensor by applying penetrating oil to the threads and using the O2 sensor socket.
• Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 lb-ft).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust clamp tool.
• Locate the catalytic converter and inspect for physical damage or blockage.
• If replacement is necessary, disconnect the exhaust pipe from the catalytic converter using the socket set.
• Remove the catalytic converter from its mounts and replace it with a new unit, ensuring all gaskets are in place.
• Reattach the exhaust pipe and torque bolts to the manufacturer's specifications (usually around 40 lb-ft).

4. Clear Diagnostic Codes

• Reconnect the negative terminal of the battery.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.

5. Test Drive

• Take the vehicle for a test drive to allow the system to recalibrate and check for any check engine light reoccurrence.