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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, safety glasses, gloves.
• Disconnect the vehicle's battery to ensure safety during repairs.
• Gather replacement parts as needed based on diagnostics.

2. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (typically near the exhaust manifold and after the catalytic converter).
  2. Disconnect the electrical connectors from both sensors.
  3. Use a multimeter to measure the voltage output of each sensor. The upstream sensor should fluctuate between 0.1V and 0.9V.
  4. If either sensor is outside the normal range, replace it.

3. Examine the Catalytic Converter

• Sub-steps:
  1. Visually inspect the catalytic converter for any dents, holes, or signs of damage.
  2. If damage is found, remove the catalytic converter by loosening the bolts with a socket set and separating it from the exhaust system.
  3. Inspect the internal structure of the converter. If it appears clogged or damaged, replace the catalytic converter with a new one, ensuring it meets OEM specifications.

4. Reassemble Exhaust Components

• Sub-steps:
  1. Reinstall the catalytic converter and tighten all bolts to the manufacturer's torque specifications (consult the service manual for exact torque values).
  2. Reconnect the oxygen sensor connectors.
  3. Reconnect the battery terminals securely.

5. Clear Codes and Test Drive

• Sub-steps:
  1. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  2. Start the vehicle and allow it to reach operating temperature.
  3. Perform a test drive to ensure the check engine light does not reappear and monitor for any symptoms.