how to fix P0420 code on Tesla Model 3 Original (2017-2023)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the ignition is off.
• Disconnect the negative terminal of the 12V battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Sensors: Use an oxygen sensor socket to carefully unscrew the sensors from the exhaust system.
3. Inspect the Threads: Check the threads of the sensors and the mounting holes for damage or corrosion.
4. Install New Sensors: Apply anti-seize compound to the threads of the new sensors and install them, tightening to the manufacturer’s specifications (typically around 30 Nm or 22 lb-ft).
5. Reconnect Electrical Connectors: Ensure the connectors are clean and securely attached.

3. Inspect and Replace the Catalytic Converter

1. Remove Exhaust Components: If necessary, disconnect any exhaust components obstructing access to the catalytic converter (use a socket set).
2. Inspect the Catalytic Converter: Check for physical damage or signs of clogging.
3. Replace the Catalytic Converter: If damaged, install a new catalytic converter. Ensure all gaskets are replaced and components are torqued to manufacturer specifications.
4. Reconnect Exhaust Components: Reattach any exhaust parts removed, ensuring a leak-free seal.

4. Reset the ECM

1. Reconnect the Battery: Reconnect the negative terminal of the battery.
2. Clear the Codes: Use an OBD-II scanner to erase the P0420 code from the ECM.
3. Test Drive: Drive the vehicle under various conditions to allow the ECM to run monitors and confirm if the issue is resolved.