how to diagnose P0420 code on my Honda CR-V Fifth Generation (2017-2022)

Solution

1. Preparation

• Gather tools and parts.
• Make sure the vehicle is on a level surface.
• Disconnect the battery to ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually near the exhaust manifold and after the catalytic converter).
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors and torque them to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• Sub-steps:
  1. Raise the vehicle safely using jack stands.
  2. Remove the exhaust heat shield, if present, to access the catalytic converter.
  3. Unscrew and remove the bolts securing the catalytic converter to the exhaust system.
  4. If the converter is welded in, use an exhaust pipe cutter to remove the old unit.
  5. Install the new catalytic converter, ensuring proper alignment and tightening bolts to the specified torque (usually around 25-30 ft-lbs).
  6. Reattach the exhaust heat shield.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and let it run for a few minutes.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.