what does it mean if my Toyota Highlander Fourth Generation (2020-present) is throwing a P0420 code?

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to avoid electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to carefully remove the sensors.
  4. Install new oxygen sensors, tightening them to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tools (if necessary)
• Sub-steps:
  1. Inspect the catalytic converter for physical damage or discoloration.
  2. If replacement is necessary, disconnect the exhaust pipes and any heat shields attached to the catalytic converter.
  3. Remove the old catalytic converter from the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  5. Torque all bolts and connections to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code from the system.