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

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the vehicle battery to ensure safety.
• Raise the vehicle securely using jack stands.

2. Inspect Exhaust System

• Tools Required: Visual inspection tools, flashlight.
• Inspect the exhaust system for leaks, damage, or loose connections.
• Repair or replace any damaged components found during inspection.

3. Test Oxygen Sensors

• Tools Required: Multimeter.
• Disconnect the upstream and downstream oxygen sensors.
• Use the multimeter to check the voltage output of the upstream sensor; it should fluctuate between 0.1V and 0.9V.
• If the upstream sensor is faulty, replace it.
• Check the downstream sensor; it should have a stable voltage reading. Replace it if it is faulty.

4. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Remove the exhaust pipe leading to the catalytic converter.
• Inspect the catalytic converter for physical damage or clogging.
• If replacement is needed, install a new catalytic converter according to manufacturer specifications.
• Torque the bolts to the manufacturer's specifications.

5. Reset the ECU

• Reconnect the battery.
• Use an OBD-II scanner to clear the P0420 code from the ECU.