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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor:
  1. Locate the sensor before the catalytic converter.
  2. Use the O2 sensor socket to carefully unscrew the sensor from its mounting.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Hand-tighten the sensor, then torque to manufacturer specifications (typically around 30 ft-lbs).
• Repeat the above steps for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Socket set, exhaust pipe cutter (if necessary), gasket scraper, torque wrench
• Remove the catalytic converter:
  1. Loosen and remove bolts securing the catalytic converter to the exhaust system using a socket set.
  2. If necessary, cut the exhaust pipe to remove the catalytic converter.
• Install the new catalytic converter:
  1. Ensure the mating surfaces are clean.
  2. Position the new catalytic converter and secure it with bolts, tightening to the manufacturer's torque specifications.
  3. Replace any gaskets as required to prevent leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.