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

Solution

1. Preparation

• Gather tools and parts as required for the repair.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors.
2. Disconnect the wiring harness from each sensor.
3. Use an oxygen sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
4. Install new oxygen sensors by threading them into the respective locations and tightening them to the manufacturer's torque specifications (usually around 30 Nm).
5. Reconnect the wiring harness to each oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If testing indicates the catalytic converter is faulty, disconnect the exhaust system at the flange before the converter.
2. Remove any heat shields or mounting brackets that obstruct access to the catalytic converter.
3. Cut or unbolt the catalytic converter from the exhaust pipes.
4. Install the new catalytic converter in the reverse order of removal, ensuring all gaskets and seals are replaced.
5. Reattach any heat shields and brackets, tightening to the specified torque.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory.
3. Start the vehicle and allow it to reach operating temperature.