what does it mean if my Toyota Highlander Third Generation (2014-2019) has a P0420 code?

Solution

1. Preparation

• Gather tools and parts needed.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical short circuits.

2. Inspect and Repair Exhaust System

• Tools Required: Socket set, jack stands, exhaust pipe wrench
• Inspect the exhaust system for leaks, particularly around the catalytic converter and oxygen sensors.
  • If any leaks are found, repair or replace the affected sections of the exhaust.

3. Replace Faulty Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• If the oxygen sensor readings are abnormal, remove the faulty sensor(s):
  • Disconnect the wiring harness from the sensor.
  • Use the O2 sensor socket to unscrew and remove the sensor.
  • Install the new sensor, ensuring it is torqued to the manufacturer's specifications.
  • Reconnect the wiring harness.

4. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting tool (if required), new gaskets
• If the catalytic converter is failing, it will need to be replaced:
  • Disconnect any oxygen sensors from the catalytic converter.
  • Remove any bolts or clamps securing the catalytic converter to the exhaust system.
  • If necessary, cut away any damaged sections.
  • Install the new catalytic converter using new gaskets and ensure all connections are tight.

5. Reconnect Battery and Clear Codes

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.