how to fix P0420 code on my Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new sensors by threading them into place and tightening to manufacturer specifications (typically 30 Nm or 22 lb-ft).
  5. Reconnect electrical connectors to both oxygen sensors.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  1. Remove any heat shields or protective coverings around the catalytic converter.
  2. Use a socket set to remove the bolts securing the catalytic converter to the exhaust manifold and exhaust pipe.
  3. Carefully detach the catalytic converter from the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment and fitment.
  5. Torque the bolts to manufacturer specifications (typically 40 Nm or 30 lb-ft).
  6. Reinstall any heat shields removed.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.