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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench, multimeter.
• Sub-steps:
  1. Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors using the O2 sensor socket.
  2. Inspect the sensors for damage or contamination.
  3. Test the sensors with a multimeter to check their resistance and voltage output. Replace if faulty.
  4. Install new oxygen sensors, torquing to the manufacturer's specifications, typically around 30 ft-lbs.

3. Check and Replace the Catalytic Converter

• Tools Required: Jack and jack stands, socket set, exhaust gasket.
• Sub-steps:
  1. Raise the vehicle securely with jack stands.
  2. Remove the bolts securing the catalytic converter to the exhaust system using the socket set.
  3. Inspect the catalytic converter for physical blockages or damage.
  4. If replacement is necessary, install the new catalytic converter with a new exhaust gasket, tightening the bolts to the specified torque (usually around 25-30 ft-lbs).

4. Clear Codes and Test

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the vehicle and monitor for any check engine light reactivation.