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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Remove the upstream oxygen sensor (before the catalytic converter) and inspect for damage.
  • If faulty, replace it with a new OEM or quality aftermarket sensor.
• Repeat for the downstream oxygen sensor (after the catalytic converter) if it shows signs of failure.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if needed).
• Raise the vehicle securely on jack stands and remove the heat shield if applicable.
• Unbolt the catalytic converter from the exhaust system, using penetrating oil if bolts are corroded.
• Inspect the catalytic converter for physical damage or contamination.
• If damaged, replace it with a new OEM catalytic converter, ensuring proper alignment during installation.

4. Clear Codes and Test

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the ECM.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to monitor performance and ensure the check engine light does not reappear.