how to fix P0420 code on my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Diagnose Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream oxygen sensor using a socket set.
• Test the sensor output: Connect the multimeter leads to the sensor terminals, and start the engine. The voltage should fluctuate between 0.1V and 0.9V. If it does not, replace the sensor.
• Repeat the test for the downstream oxygen sensor. If readings are out of range, replace the sensor.

3. Inspect the Catalytic Converter

• Tools Required: Socket set, jack and jack stands
• Raise the vehicle using a jack and secure it with jack stands.
• Visually inspect the catalytic converter for any dents, cracks, or signs of overheating.
• If the catalytic converter appears damaged or if the vehicle has high mileage (over 100,000 miles), consider replacing it.

4. Replace the Catalytic Converter (if needed)

• Parts Required: New catalytic converter (ensure it meets OEM specifications)
• Remove the exhaust bolts securing the catalytic converter to the exhaust system using a socket set.
• Carefully detach the catalytic converter from the vehicle.
• Install the new catalytic converter in the reverse order, ensuring all gaskets and seals are properly placed.
• Torque the exhaust bolts to the manufacturer’s specifications.

5. Clear the Codes and Test the Vehicle

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it reach operating temperature.
• Perform a test drive to monitor for any reoccurrence of the check engine light.