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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the vehicle battery to ensure safety.
• Raise the vehicle using a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.

• Remove the upstream oxygen sensor:

  1. Locate the upstream oxygen sensor (before the catalytic converter).
  2. Use an O2 sensor socket to unscrew and remove the sensor.
  3. Install the new oxygen sensor and torque it to the manufacturer’s specifications (typically around 30 ft-lbs).

• Remove the downstream oxygen sensor:

  1. Locate the downstream oxygen sensor (after the catalytic converter).
  2. Use the O2 sensor socket to unscrew and remove the sensor.
  3. Install the new oxygen sensor and torque it to specifications.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).

• Remove the catalytic converter:

  1. Disconnect the exhaust pipes on both sides of the catalytic converter.
  2. If necessary, cut exhaust pipes carefully using an exhaust pipe cutter.
  3. Remove bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.

• Install the new catalytic converter:

  1. Position the new catalytic converter and secure it using new gaskets and bolts.
  2. Torque all bolts to the manufacturer's specifications (typically around 30-40 ft-lbs).
  3. Reconnect any exhaust pipes and ensure there are no leaks.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code.
• Test drive the vehicle for at least 20 minutes to ensure the check engine light does not reappear.