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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety glasses, gloves.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid any electrical shorts.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: Oxygen sensor socket, torque wrench.
• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Remove the upstream oxygen sensor using the oxygen sensor socket; if it is damaged or malfunctioning, replace it.
  • Torque the new sensor to the manufacturer's specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor if needed.

3. Inspect Catalytic Converter

• Check for any signs of external damage or blockage in the catalytic converter.
• If the converter shows signs of failure (e.g., rattling noise, discoloration), it should be replaced.
• To replace, unbolt the exhaust manifold or downstream pipe from the catalytic converter.
• Install the new catalytic converter, ensuring all gaskets are in good condition and properly aligned.
  • Torque bolts to the vehicle manufacturer’s specifications.

4. Clear the Codes

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and allow it to reach operating temperature.