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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:

   • The upstream sensor is usually located before the catalytic converter, and the downstream sensor is located after it.

2. Remove the Upstream Oxygen Sensor:

   • Use an oxygen sensor socket or wrench to unscrew the upstream sensor.
   • Disconnect the electrical connector carefully.

3. Install the New Upstream Oxygen Sensor:

   • Apply anti-seize compound to the threads of the new sensor.
   • Install and torque to the manufacturer's specifications (typically around 30 ft-lbs).
   • Reconnect the electrical connector.

4. Repeat for the Downstream Oxygen Sensor:

   • Follow the same steps to replace the downstream oxygen sensor.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Remove the Exhaust Components:

   • Loosen bolts and remove any clamps securing the exhaust system before the catalytic converter.
   • Carefully detach the catalytic converter from the exhaust pipes.

2. Inspect the Catalytic Converter:

   • Check for any signs of damage, such as dents or a rattling noise indicating internal failure.

3. Install the New Catalytic Converter:

   • Position the new catalytic converter in place.
   • Secure it with new gaskets and bolts, tightening to the manufacturer’s specifications.

4. Reconnect the Battery

• Reconnect the negative terminal of the battery and ensure it is secured properly.

5. Clear the Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.