my Toyota Highlander Third Generation (2014-2019) has a P0420 code, what should I check?

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to ensure safety while working.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Disconnect the electrical connector for each sensor.
  3. Use an O2 sensor socket to remove the sensors from the exhaust.
  4. Inspect the sensors for damage; replace any faulty sensors with new ones.
  5. Install the new sensors and reconnect the electrical connectors.

3. Inspect and Clean Catalytic Converter

• Tools Required: Wrench set, exhaust cleaner, safety glasses.
• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Inspect the converter for physical damage or signs of clogging.
  3. If excessive carbon buildup is present, clean the converter using an appropriate exhaust cleaner.
  4. Reinstall any components removed during inspection.

4. Reconnect Battery and Clear Codes

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