how to troubleshoot Tesla Model 3 Highland (2024-present) with P0420 error code

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Remove the upstream oxygen sensor:
  1. Locate the upstream oxygen sensor near the exhaust manifold.
  2. Apply penetrating oil to the sensor threads and allow it to soak.
  3. Use the O2 sensor socket to unscrew the sensor.
• Install the new oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Screw it into place and tighten to manufacturer specifications (usually around 30-35 ft-lbs).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Remove the catalytic converter:
  1. Locate the catalytic converter and disconnect any heat shields.
  2. Use the socket set to remove the bolts securing the catalytic converter to the exhaust system.
  3. Carefully lower the converter and inspect for damage.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place.
  2. Secure it using the original bolts and torque to manufacturer specifications.
  3. Reattach any heat shields previously removed.

4. Clear Error Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any error codes from the system.
• Start the engine and allow it to reach operating temperature.