how to diagnose a P0420 code on my Tesla Model 3 Original (2017-2023)?

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the vehicle’s 12V battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Instructions:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Apply penetrating oil to the sensor threads and wait a few minutes.
  3. Disconnect the electrical connectors from the oxygen sensors.
  4. Use the O2 sensor socket to remove the sensors.
  5. Install the new sensors in the reverse order, ensuring they are torqued to manufacturer specifications (typically around 30 lb-ft).

3. Examine and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust hanger removal tool, torque wrench, gasket scraper.
• Instructions:
  1. Inspect the catalytic converter for any signs of damage or blockage.
  2. If replacement is necessary, remove the exhaust hangers using the exhaust hanger removal tool.
  3. Disconnect the catalytic converter from the exhaust pipes and any attached sensors.
  4. Remove any old gaskets and clean the mating surfaces using a gasket scraper.
  5. Install the new catalytic converter, ensuring all connections are secure and torqued to specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle’s 12V battery.
• Use the OBD-II scanner to clear the P0420 code from the ECM.