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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Remove the upstream oxygen sensor (before the catalytic converter).
  • Use the O2 sensor socket to unscrew the sensor.
  • Disconnect the wiring harness from the sensor.
• Install the new upstream O2 sensor.
  • Torque the new sensor to the manufacturer's specification (usually around 30 lb-ft).
  • Reconnect the wiring harness.
• Repeat the process for the downstream oxygen sensor (after the catalytic converter) if required.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary), gasket scraper.
• Raise the vehicle securely on jack stands.
• Remove any heat shields covering the catalytic converter.
• Disconnect the exhaust pipes connected to the catalytic converter.
  • Use a socket set to unbolt the flanges or cut the pipes if needed.
• Remove the old catalytic converter.
• Clean the mounting surfaces where the new converter will be installed.
• Install the new catalytic converter and reconnect the exhaust.
  • Ensure all bolts are torqued according to specifications (usually around 30 lb-ft).

4. Final Checks

• Reconnect the battery.
• Clear the P0420 code using the OBD-II scanner.
• Start the engine and allow it to reach operating temperature.