how to fix the P0420 code on my 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 negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use an O2 sensor socket to remove both sensors from their respective locations.
  3. Inspect the sensors for signs of damage or contamination.
  4. Install new oxygen sensors, tightening them to the manufacturer's specifications (usually around 30 Nm).
  5. Reconnect the wiring harness.

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

• Tools Required: Socket set, jack and jack stands.
• Sub-steps:
  1. Raise the vehicle and secure it on jack stands.
  2. Inspect the catalytic converter for physical damage or excessive carbon buildup.
  3. If replacement is necessary, remove the exhaust system components connected to the catalytic converter.
  4. Install the new catalytic converter, ensuring proper alignment and securing it with the correct torque specifications (usually around 50 Nm).
  5. Reattach any exhaust hangers and components removed during replacement.

4. Clear Error Codes

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code from the system.