how to diagnose the P0420 code in my Toyota RAV4 Fourth Generation (2013-2018)?

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Remove the upstream (pre-catalytic) oxygen sensor using the O2 sensor socket and ratchet. If it is stuck, apply penetrating oil and let it sit before attempting removal.
• Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream (post-catalytic) oxygen sensor.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter (if needed).
• Raise the vehicle using the jack and secure it with jack stands.
• Inspect the catalytic converter for physical damage or blockage. If damaged, use an exhaust pipe cutter to remove it from the exhaust system.
• Install the new catalytic converter, ensuring proper alignment and sealing with gaskets as necessary.
• Torque all bolts to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals securely.
• Use the OBD-II scanner to clear the error codes from the vehicle’s computer.