how to fix the P0420 error code on my Tesla Model Y Current (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely.

2. Inspect the Catalytic Converter

• Tools Required: Socket set, jack stands
• Using a socket set, remove the bolts securing the catalytic converter to the exhaust system.
• Visually inspect the catalytic converter for any signs of damage, such as dents or rust.
• If damaged, proceed to replace the catalytic converter.

3. Replace the Catalytic Converter (if necessary)

• Tools Required: Gasket scraper, new exhaust gaskets, torque wrench
• Clean the mounting surfaces on both ends of the catalytic converter using a gasket scraper.
• Install the new catalytic converter with new gaskets.
• Torque the bolts to the manufacturer’s specifications (typically around 30-50 lb-ft, but refer to the service manual for exact values).

4. Test the Oxygen Sensors

• Tools Required: Multimeter
• Disconnect the electrical connectors from the upstream and downstream oxygen sensors.
• Use a multimeter to test the voltage output of the oxygen sensors. The upstream sensor should fluctuate between 0.1V and 0.9V, while the downstream sensor should be more stable.
• If any sensor is out of specifications, replace it.

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the error codes from the system.
• Start the engine and let it idle for a few minutes.