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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to prevent electrical shorts.

Tools Required:

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

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Disconnect the electrical connectors from both sensors.
3. Using a socket wrench, remove the sensors from their respective locations.
4. Install the new oxygen sensors (if faulty) and torque them to the manufacturer's specifications.
5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

1. If the catalytic converter is determined to be faulty, start by loosening the bolts securing the exhaust pipe to the catalytic converter.
2. Remove any heat shields or brackets that may obstruct access to the catalytic converter.
3. Carefully lower the catalytic converter from the vehicle.
4. Install the new catalytic converter, ensuring that it is oriented correctly.
5. Reattach any heat shields or brackets removed earlier.
6. Tighten the exhaust pipe bolts to the specified torque value.

4. Reconnect Battery and Clear Codes

1. Reconnect the battery terminals, ensuring they are tight.
2. Use the OBD-II scanner to clear the P0420 code from the engine control module (ECM).