how to fix P0420 code on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle safely using jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream oxygen sensor:
  1. Locate the upstream O2 sensor near the exhaust manifold.
  2. Use the O2 sensor socket to unscrew the sensor.
  3. Install the new sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream sensor if it was found faulty.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Remove the catalytic converter:
  1. Unbolt the exhaust flanges connecting the catalytic converter to the exhaust system.
  2. If necessary, cut the exhaust pipes using an exhaust pipe cutter.
  3. Remove the old catalytic converter.
• Install the new catalytic converter:
  1. Position the new converter and secure it with the bolts.
  2. Torque the bolts to manufacturer specifications (consult service manual for specific torque values).
  3. Ensure all connections are sealed and secure.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals ensuring a tight fit.
• Use the OBD-II scanner to clear the P0420 code from the system.