how to resolve the Tesla Model 3 Highland (2024-present) error code P0420

Solution

1. Preparation

• Tools Required: OBD-II scanner, jack and jack stands, socket set, multimeter, safety glasses, gloves.
• Sub-steps:
  • Disconnect the vehicle's battery to prevent electrical shorts.
  • Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Repair Exhaust System

• Sub-steps:
  • Visually inspect the entire exhaust system from the engine to the tailpipe for leaks or damage.
  • Tighten any loose connections and replace any damaged exhaust components.
  • If the catalytic converter is damaged, you will need to replace it.

3. Test and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors on the exhaust system.
  • Disconnect the wiring harness from each sensor.
  • Use a multimeter to test the voltage output of each sensor.
  • If the readings are outside the manufacturer's specifications, replace the faulty oxygen sensor with a new one.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  • Remove the bolts securing the catalytic converter to the exhaust system.
  • Carefully detach the catalytic converter from its mounting.
  • Install the new catalytic converter, ensuring it is properly aligned.
  • Torque the bolts to the manufacturer's specifications (typically 30-40 lb-ft).

5. Reconnect Battery and Clear Codes

• Sub-steps:
  • Reconnect the battery terminals.
  • Use the OBD-II scanner to clear the error codes from the system.