how to fix P0420 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, jack and jack stands.
• Safety Warnings: Disconnect the battery before working on electrical systems. Allow the engine to cool before working on the exhaust system.

2. Inspect and Repair Exhaust Leaks

• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Visually inspect the entire exhaust system for cracks, holes, or loose connections.
  3. Repair any leaks using appropriate exhaust repair tape or replace damaged sections of the exhaust pipe.

3. Test and Replace Oxygen Sensors (if faulty)

• Sub-steps:
  1. Disconnect the electrical connectors of the upstream and downstream oxygen sensors.
  2. Use a multimeter to check the voltage output of the sensors (should fluctuate between 0.1V to 0.9V for the upstream sensor).
  3. If the readings are outside this range, replace the faulty oxygen sensor with a new one.
  4. Reconnect the electrical connectors and ensure they are secure.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. If the catalytic converter is clogged or damaged, remove it by unbolting the flanges connecting it to the exhaust system.
  2. Install the new catalytic converter, ensuring proper alignment with the exhaust pipes.
  3. Torque the bolts to the manufacturer's specifications (usually around 25-30 lb-ft).
  4. Reconnect any sensors or components removed during installation.