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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface, engage the parking brake, and allow the engine to cool.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench, penetrating oil.
• Instructions:
  1. Disconnect the negative battery terminal to avoid electrical shorts.
  2. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  3. Use penetrating oil on the sensor threads to ease removal.
  4. Remove the upstream O2 sensor and inspect for any contamination. Replace if necessary.
  5. Repeat the process for the downstream O2 sensor.
  6. Install the new sensors and torque them to the manufacturer's specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), gaskets.
• Instructions:
  1. Lift the vehicle securely using jack stands.
  2. Disconnect the exhaust pipes connected to the catalytic converter using a socket set.
  3. Remove any bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
  4. Inspect the old catalytic converter for any signs of physical damage or clogging.
  5. Install the new catalytic converter, ensuring that all gaskets are replaced.
  6. Torque all bolts to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

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