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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the vehicle's battery to prevent electrical shock.
• Allow the vehicle to cool completely before working on the exhaust system.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream (pre-catalytic) oxygen sensor using a socket wrench.
• Use the multimeter to check the sensor's voltage output; it should fluctuate between 0.1 to 0.9 volts during operation.
• If out of range, replace the oxygen sensor.

3. Inspect the Catalytic Converter

• Tools Required: Socket set, torque wrench
• Remove the bolts securing the catalytic converter using a socket set.
• Inspect the converter for physical damage, clogging, or contamination.
• If damaged, replace the catalytic converter with an OEM or equivalent part.
• Reinstall the catalytic converter, ensuring to torque bolts to manufacturer specifications (typically around 30-40 ft-lbs).

4. Clear Codes and Reconnect Battery

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code.