how to fix P0420 code in Toyota Highlander XU70 (2020-Present)?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the vehicle battery to ensure safety while working on the electrical components.

2. Inspect and Replace Oxygen Sensors

1. Remove the Oxygen Sensor
   • Use an oxygen sensor socket to carefully unscrew the upstream (pre-catalytic converter) oxygen sensor.
   • Disconnect the wiring harness from the sensor.
2. Install New Oxygen Sensor
   • Apply anti-seize compound to the threads of the new oxygen sensor.
   • Screw in the new sensor and connect the wiring harness.
   • Torque the oxygen sensor to the manufacturer's specifications (typically around 30 lb-ft) using a torque wrench.

3. Inspect and Replace the Catalytic Converter

1. Remove the Catalytic Converter
   • Loosen and remove the bolts securing the catalytic converter to the exhaust pipe and exhaust manifold using a socket set.
   • Carefully detach the catalytic converter from the vehicle.
2. Install New Catalytic Converter
   • Position the new catalytic converter in place and secure it with the bolts.
   • Ensure all gaskets are intact and use new gaskets if necessary.
   • Torque the bolts to the manufacturer's specifications (typically around 40 lb-ft).

4. Clear Diagnostic Codes

• Reconnect the vehicle battery.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.

5. Test Drive

• Take the vehicle for a test drive under various conditions to ensure the check engine light does not reappear.