how to troubleshoot a P0420 code in a Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to ensure safety during electrical work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors on the exhaust manifold and catalytic converter.
  2. Use the O2 sensor socket to unscrew the upstream sensor. Disconnect the wiring harness.
  3. Install the new upstream O2 sensor and torque to manufacturer specifications (typically around 30 lb-ft).
  4. Repeat the process for the downstream O2 sensor if it shows signs of malfunction.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust hanger removal tool.
• Sub-steps:
  1. Raise the vehicle securely using a jack and jack stands.
  2. Disconnect any exhaust hangers and clamps holding the catalytic converter in place.
  3. Remove the catalytic converter from the exhaust system using a socket set.
  4. Install the new catalytic converter, ensuring proper alignment and torque (typically around 40 lb-ft).
  5. Reattach the exhaust hangers and clamps securely.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.