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

Solution

1. Preparation

• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Gather tools and parts needed for the repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: OBD-II scanner, socket set, oxygen sensor wrench, multimeter.
• Sub-steps:
  1. Disconnect the battery to prevent electrical shorts.
  2. Locate the upstream and downstream oxygen sensors on the exhaust system.
  3. Using the oxygen sensor wrench, carefully unscrew and remove the sensors.
  4. Test the sensor outputs with a multimeter. Replace any sensors that are out of specification.
  5. Install new sensors by threading them into place and tightening to the manufacturer's torque specifications (typically around 30 Nm).
  6. Reconnect the battery.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hangers tool.
• Sub-steps:
  1. Lift the vehicle using a jack and secure it with jack stands.
  2. Locate the catalytic converter in the exhaust system.
  3. Inspect the converter for physical damage, dents, or rust.
  4. If replacement is needed, disconnect the exhaust pipes and any mounting brackets using the socket set.
  5. Remove the old catalytic converter.
  6. Install the new catalytic converter, ensuring that all connections are secure and properly torqued (usually 25-30 Nm).
  7. Reinstall any exhaust hangers that were removed.