how to fix P0420 code on Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Jack and jack stands
• Safety goggles and gloves

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from the sensors.
  3. Use a socket wrench to remove the sensors from the exhaust system.
  4. Install new oxygen sensors and torque them to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Examine the Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage or excessive carbon buildup.
  2. If damaged, remove the catalytic converter by unbolting it from the exhaust system.
  3. Install a new catalytic converter, ensuring it is compatible with the vehicle's make and model.
  4. Torque the bolts to the specified settings (usually around 30-40 ft-lbs).

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
  2. Start the engine and let it idle for a few minutes.
  3. Take the vehicle for a test drive to monitor performance and check for the check engine light.