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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, safety glasses, gloves.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery by removing the negative terminal.

2. Inspect and Replace the Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use a socket to remove the upstream oxygen sensor; inspect for damage or contamination.
  3. Install the new upstream oxygen sensor and torque to manufacturer specifications (usually around 30 lb-ft).
  4. Repeat the process for the downstream oxygen sensor.

3. Check and Replace the Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for physical damage or excessive carbon buildup.
  2. If necessary, remove the catalytic converter by unbolting it from the exhaust manifold and the exhaust pipe.
  3. Install the new catalytic converter, ensuring all gaskets are in place, and torque bolts to manufacturer specifications (typically around 30-40 lb-ft).
  4. Reconnect the exhaust system and ensure all connections are secure.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.