why does my Tesla Model 3 Original (2017-2023) show error code P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety.
• Allow the vehicle to cool down completely.

2. Inspect and Test Oxygen Sensors

• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Disconnect the electrical connectors from both sensors.
• Use a multimeter to test the sensors:
  • Set the multimeter to the appropriate voltage setting.
  • Measure the voltage output of the upstream sensor while the engine is running; it should fluctuate between 0.1 to 0.9 volts.
  • Repeat for the downstream sensor; it should generally remain stable if the catalytic converter is functioning properly.
• Replace any faulty oxygen sensors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• If the oxygen sensors are functioning correctly, inspect the catalytic converter.
• Remove any heat shields if applicable.
• Unbolt the catalytic converter from the exhaust system (ensure appropriate torque specifications are followed).
• Inspect the catalytic converter for any physical damage or blockage.
• If damaged, replace with a new catalytic converter, ensuring it's compatible with the Tesla Model 3.
• Reinstall and torque bolts to manufacturer specifications.

4. Clear Error Codes

• Reconnect the battery.
• Use an OBD-II scanner to clear the error codes from the system.
• Perform a short test drive to ensure the error code does not return.