how to resolve P0420 code in my Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts during inspection.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Remove the upstream (pre-catalytic converter) oxygen sensor.
  • Use the O2 sensor socket to unscrew the sensor from the exhaust pipe.
• Inspect the sensor for damage or contamination.
• If faulty, install a new oxygen sensor.
  • Torque the new sensor to the manufacturer’s specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper, high-temperature exhaust sealant.
• If oxygen sensors are functioning correctly, inspect the catalytic converter for physical damage.
• Remove the catalytic converter using a socket set.
  • Cut the exhaust pipe if necessary, ensuring to leave enough pipe for reinstallation.
• Replace with a new catalytic converter that meets OEM specifications.
  • Use a new gasket and high-temperature exhaust sealant at the joints.
  • Torque the bolts to manufacturer’s specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery ensuring all connections are secure.
• Use the OBD-II scanner to clear the P0420 code and any related codes.

5. Perform a Test Drive

• Drive the vehicle under various conditions (city and highway) to allow the ECU to recalibrate.
• Monitor the vehicle for any reoccurrence of the P0420 code.