how to diagnose P0420 code Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Unplug the electrical connectors from both sensors.
  3. Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
  4. Inspect the threads for damage; clean if necessary.
  5. Install the new sensors, ensuring they are torqued to the manufacturer's specifications (usually around 30 lb-ft).
  6. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust hangers removal tool.
• Sub-steps:
  1. Raise the vehicle securely on jack stands and remove the underbody shield if present.
  2. Visually inspect the catalytic converter for physical damage or signs of overheating.
  3. If damaged, unbolt the catalytic converter from the exhaust system (usually at the flange connections).
  4. Remove any exhaust hangers using the exhaust hangers removal tool.
  5. Install the new catalytic converter, ensuring proper alignment and torque (usually around 25 lb-ft).
  6. Reattach any exhaust hangers and the underbody shield.

4. Reset the ECU

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECU.
  3. Perform a test drive to ensure the code does not return.