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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Tools Required:
  • OBD-II scanner
  • Socket set
  • Torque wrench
  • Multimeter
  • Safety goggles
  • Gloves
• Ensure the vehicle is on a flat surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Disconnect the negative battery terminal to avoid electrical shorts.
  2. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  3. Unplug the electrical connectors from both oxygen sensors.
  4. Use a socket wrench to remove the sensors from the exhaust manifold and catalytic converter respectively.
  5. Install the new oxygen sensors and torque them to the manufacturer's specifications (usually around 30 lb-ft).
  6. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Visually inspect the catalytic converter for any physical damage or signs of clogging.
  2. If replacement is required, use a socket set to remove the bolts securing the catalytic converter to the exhaust system.
  3. Carefully remove the old catalytic converter and clean the mating surfaces on the exhaust pipes.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque the bolts to the manufacturer's recommended specifications (typically between 30-50 lb-ft depending on the model).

4. Reset the Engine Control Module (ECM)

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the engine and allow it to reach normal operating temperature.