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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery (negative terminal) to avoid electrical hazards.
• Ensure the vehicle is cool, and raise it using jack stands for better access to the exhaust system.

2. Inspect and Repair Exhaust Leaks

• Sub-steps:
  • Visually inspect the entire exhaust system for signs of rust, holes, or loose connections.
  • Use a smoke machine or soapy water to identify leaks, particularly near the catalytic converter.
  • Repair or replace any damaged sections of the exhaust system as necessary (e.g., exhaust pipes, gaskets).

3. Check and Replace Oxygen Sensors

• Sub-steps:
  • Remove the upstream (pre-catalytic converter) oxygen sensor using a socket wrench.
  • Inspect the sensor for carbon buildup or damage.
  • Replace the oxygen sensor with a new one if found faulty.
  • Repeat the process for the downstream (post-catalytic converter) oxygen sensor if it is also suspected to be malfunctioning.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  • If the catalytic converter is determined to be faulty, unbolt it from the exhaust system.
  • Carefully remove the old catalytic converter and install the new one, ensuring proper alignment with existing exhaust components.
  • Torque all bolts to the manufacturer’s specifications.

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the fault codes and reset the check engine light.