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 to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors on the exhaust.
  • Use a socket wrench to remove the oxygen sensors.
  • Inspect the sensors for damage or contamination.
  • Replace with new sensors if necessary; ensure proper torque (typically 30 ft-lbs).
  • Reconnect electrical connectors.

3. Inspect and Clean or Replace the Catalytic Converter

• Sub-steps:
  • Locate the catalytic converter in the exhaust system.
  • Visually inspect for any physical damage or blockages.
  • If cleaning is required, use a catalytic converter cleaner and follow the product instructions.
  • If replacement is needed, unbolt the catalytic converter from the exhaust system using a socket set.
  • Install the new catalytic converter, ensuring proper alignment and torque (typically 30-40 ft-lbs for mounting bolts).
  • Reconnect all exhaust components.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  • Reconnect the battery terminals.
  • Use the OBD-II scanner to clear the P0420 code from the system.