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

Solution

1. Preparation

• Gather all required tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Locate the upstream and downstream oxygen sensors.
• Disconnect the electrical connectors from both sensors.
• Remove the upstream oxygen sensor using the O2 sensor socket.
• Install the new upstream oxygen sensor and torque to manufacturer specifications.
• Repeat the process for the downstream oxygen sensor.

3. Repair or Replace Catalytic Converter

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if necessary).
• Inspect the catalytic converter for damage or blockage.
• If replacement is necessary, support the exhaust system with jack stands.
• Remove any heat shields or brackets securing the catalytic converter.
• Cut the exhaust piping if it is welded, then remove the old catalytic converter.
• Install the new catalytic converter, ensuring proper alignment and sealing.
• Reattach any heat shields and secure all connections.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.
• Start the vehicle and perform a test drive to ensure the engine runs smoothly and the check engine light does not reappear.