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

Solution

1. Preparation

• Gather tools and replacement parts as needed.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Repair Exhaust Leaks

• Sub-steps:
  • Identify and mark any leaks found during inspection.
  • Use exhaust sealant or replace damaged sections of the exhaust pipe.

3. Replace Oxygen Sensors

• Sub-steps:
  • Disconnect the battery negative terminal.
  • Remove the connector from the upstream and downstream oxygen sensors.
  • Unbolt the sensors from the exhaust system using a socket wrench.
  • Install the new oxygen sensors, ensuring they are tightened to the manufacturer’s specifications (usually around 30 lb-ft).
  • Reconnect the battery terminal.

4. Replace Catalytic Converter (if needed)

• Sub-steps:
  • Disconnect the battery negative terminal.
  • Remove the exhaust pipe connected to the catalytic converter.
  • Unbolt the catalytic converter from the exhaust manifold and any mounting brackets.
  • Install the new catalytic converter, ensuring proper alignment and torque specifications (usually around 30-40 lb-ft for flange bolts).
  • Reconnect the exhaust pipe securely.

5. Clear Diagnostic Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory after repairs.