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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Safety gloves and goggles

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the sensors: Carefully unplug the electrical connectors from both oxygen sensors.
3. Remove the sensors: Use a socket wrench to unscrew the sensors from their respective locations.
4. Install new sensors: Apply anti-seize compound to the threads of the new sensors and install them in the same location, tightening to the manufacturer's specified torque.
5. Reconnect electrical connectors: Ensure the connectors are securely plugged back in.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust components: If the catalytic converter is faulty, use a socket set to remove the bolts securing the catalytic converter to the exhaust system.
2. Inspect the old catalytic converter: Check for any signs of damage, clogging, or excessive carbon buildup.
3. Install a new catalytic converter: Position the new catalytic converter in place, aligning it with the exhaust system.
4. Secure with bolts: Tighten the bolts to the manufacturer's torque specifications to ensure a proper seal.
5. Reconnect exhaust components: Ensure all exhaust components are reconnected properly.

4. Final Checks

1. Reconnect the battery: Ensure all connections are tight and secure.
2. Clear the codes: Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
3. Test drive the vehicle: Drive the vehicle for a sufficient distance to verify that the check engine light does not reappear.