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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the exhaust system to cool to avoid burns.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Remove the upstream oxygen sensor:
  • Locate the upstream sensor before the catalytic converter.
  • Use the O2 sensor socket to unscrew it.
• Install the new oxygen sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Install and torque to manufacturer specifications (usually around 30 lb-ft).
• Repeat for the downstream sensor if it shows signs of failure.

3. Replace Catalytic Converter (if necessary)

• Tools Required: Exhaust pipe cutter, socket set, torque wrench, gasket scraper.
• Disconnect the exhaust system:
  • Use the exhaust pipe cutter to carefully cut the exhaust pipe before and after the catalytic converter.
• Remove the old catalytic converter:
  • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
• Install the new catalytic converter:
  • Position the new catalytic converter and secure it with bolts.
  • Torque bolts to manufacturer specifications (typically around 30 lb-ft).
• Reconnect the exhaust system and ensure all connections are secure.

4. Reset the ECU

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the ECU.