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

Solution

1. Preparation

• Gather all tools and parts needed for repair.
• Disconnect the vehicle's battery to prevent any electrical issues during the service.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

• Locate the upstream and downstream oxygen sensors located before and after the catalytic converter.
• Use an O2 sensor socket to remove the sensors.
• Check the wiring and connectors for damage and replace if necessary.
• Install new oxygen sensors, ensuring they are torqued to manufacturer's specifications (typically around 30-40 lb-ft).
• Reconnect the battery.

3. Inspect or Replace the Catalytic Converter

• If the oxygen sensors are functioning correctly, proceed to inspect the catalytic converter.
• Remove any heat shields or brackets to access the catalytic converter.
• Inspect for physical damage or clogging.
• If replacement is necessary, unbolt the catalytic converter from the exhaust system and install a new unit, torquing bolts to specifications (usually around 30-40 lb-ft).
• Reinstall any heat shields or brackets removed during the process.

4. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code from the system.
• Conduct a test drive to ensure the vehicle operates correctly and monitor for the reappearance of the check engine light.