how to fix P0420 code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery by removing the negative terminal.

2. Inspect and Replace Oxygen Sensors

• Tools Required:
  • O2 sensor socket
  • Ratchet and extensions
• Steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Use the O2 sensor socket to carefully unscrew the upstream sensor.
  3. Inspect the sensor for damage; replace if necessary.
  4. Install the new sensor by threading it in and tightening it to the manufacturer's torque specification (generally around 30 lb-ft).
  5. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required:
  • Socket set
  • Torque wrench
  • Exhaust gasket
• Steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  3. Inspect the catalytic converter for signs of damage or blockage.
  4. If replacement is needed, install a new catalytic converter with a new exhaust gasket, ensuring all bolts are torqued to the manufacturer's specifications (typically around 30 lb-ft).
  5. Reconnect the exhaust system securely.

4. Verify Exhaust System Integrity

• Tools Required:
  • Exhaust leak detection tool
• Steps:
  1. Check for any leaks in the exhaust system that could affect sensor readings.
  2. Use the detection tool to confirm the integrity of the system.

5. Reconnect Battery and Clear Codes

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