my Tesla Model 3 Highland (2024-present) has a check engine light with code P0420

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the vehicle to cool down to prevent burns.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket wrench, multimeter, torque wrench.
• Sub-steps:
  • Locate the upstream and downstream oxygen sensors.
  • Unplug the electrical connectors from both sensors.
  • Remove the upstream oxygen sensor using the O2 sensor socket wrench.
  • Test the new oxygen sensor with a multimeter to ensure it meets specifications before installation.
  • Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
  • Repeat the process for the downstream oxygen sensor if necessary.

3. Examine and Clean/Replace Catalytic Converter

• Tools Required: Jack and jack stands, exhaust pipe cutter, wrench set.
• Sub-steps:
  • Raise the vehicle safely using jack stands and remove any underbody panels if necessary.
  • Inspect the catalytic converter for physical damage or blockage.
  • If replacement is needed, disconnect the exhaust pipes from both ends of the catalytic converter using an exhaust pipe cutter.
  • Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  • Tighten all connections securely and check for leaks.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  • Reconnect the negative battery terminal.
  • Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  • Start the vehicle and perform a test drive to ensure everything is functioning correctly.