why does my Tesla Model 3 Highland (2024-present) display show error code P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the parking brake is engaged.

2. Inspect and Replace Oxygen Sensors

1. Disconnect Battery:

   • Use a wrench to disconnect the negative terminal of the battery to prevent electrical shorts.

2. Remove the Oxygen Sensors:

   • Locate the upstream and downstream oxygen sensors.
   • Use an oxygen sensor socket to remove the sensors from the exhaust system.

3. Install New Oxygen Sensors:

   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and tighten them to the manufacturer’s specifications (usually 30-40 lb-ft of torque).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components:

   • If the catalytic converter needs replacement, unbolt the exhaust components connected to it.
   • Use a socket set to remove the bolts and carefully detach the catalytic converter.

2. Install New Catalytic Converter:

   • Position the new catalytic converter in place.
   • Bolt it securely, ensuring to follow the manufacturer's torque specifications.

4. Clear Error Codes

1. Reconnect Battery:

   • Reconnect the negative terminal of the battery.

2. Clear Codes:

   • Use the OBD-II scanner to clear the error codes from the vehicle’s memory.

5. Test Drive

• Take the vehicle for a test drive to ensure normal operation and check that the check engine light does not reappear.