why is my Toyota RAV4 Fifth Generation (2019-present) check engine light on with code P0420

Solution

1. Preparation

• Gather necessary tools and parts, and ensure the vehicle is parked on a level surface.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust system.
  4. Install new oxygen sensors, applying anti-seize compound to the threads if required.
  5. Reconnect the electrical connectors to both sensors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. If oxygen sensors are functioning correctly, inspect the catalytic converter for internal damage.
  2. Remove any heat shields or mounts preventing access to the catalytic converter.
  3. Disconnect the exhaust pipes at the inlet and outlet of the catalytic converter using a socket set.
  4. Replace the old catalytic converter with a new one, ensuring proper alignment.
  5. Reconnect the exhaust system and tighten all bolts to the manufacturer's specifications (typically 25-30 lb-ft).

4. Reset the Engine Control Unit (ECU)

• Sub-steps:
  1. Reconnect the battery cables.
  2. Use the OBD-II scanner to clear the P0420 code from the ECU.
  3. Start the vehicle and let it reach operating temperature.