how to fix P0420 code in Toyota Highlander XU70 (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 negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Exhaust System

• Tools Required: Socket set, jack stands, exhaust leak detection fluid.
• Sub-steps:
  1. Raise the vehicle using a jack and support it with jack stands.
  2. Visually inspect the exhaust system from the engine to the tailpipe for any cracks or loose connections.
  3. If leaks are found, use exhaust sealant or replace damaged sections of the exhaust pipe.

3. Test and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, multimeter.
• Sub-steps:
  1. Using the O2 sensor socket, carefully remove the upstream and downstream oxygen sensors.
  2. Test the sensors with a multimeter to ensure they are operating within specifications (check resistance and voltage outputs).
  3. Replace any faulty oxygen sensors with new ones, ensuring proper torque specifications (usually around 30-40 ft-lbs).

4. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting tool (if required), exhaust clamps.
• Sub-steps:
  1. If the catalytic converter is determined to be faulty (based on temperature tests or O2 sensor readings), unbolt it from the exhaust system.
  2. Install the new catalytic converter, ensuring proper alignment and sealing.
  3. Reconnect any sensors and exhaust hangers removed during the process.

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECM.