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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle’s battery to prevent any electrical issues during repair.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter.
• Remove the connectors from the upstream and downstream oxygen sensors.
• Use the multimeter to check the voltage output of the upstream sensor; it should fluctuate between 0.1V to 0.9V during operation.
• If the upstream sensor is faulty, replace it with a new sensor.

3. Check and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, penetrating oil.
• If the catalytic converter is clogged or damaged, it will need to be replaced.
• Use penetrating oil to loosen bolts connecting the exhaust system to the catalytic converter.
• Remove the bolts and disconnect the exhaust pipe from both ends of the catalytic converter.
• Install the new catalytic converter by reversing the removal process. Ensure all bolts are torqued to manufacturer specifications.

4. Reconnect and Reset

• Reconnect the battery.
• Reconnect the oxygen sensor connectors.
• Use the OBD-II scanner to clear the P0420 code from the system.