Honda Pilot Third Generation (2016-present) P0420 code what does it mean?

Solution

1. Preparation

• Gather tools and safety equipment.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool down before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor.
  • Use the O2 sensor socket to unscrew the sensor.
  • Inspect the sensor for damage or carbon buildup.
• Install a new upstream oxygen sensor.
  • Torque to manufacturer's specification (typically around 30-40 lb-ft).
• Repeat the process for the downstream (post-catalytic) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket, and possibly a saw for cutting exhaust pipes.
• Remove any mounting bolts securing the catalytic converter.
• Inspect the catalytic converter for signs of blockage or damage.
• If replacement is necessary:
  • Remove the old catalytic converter and clean the mounting surfaces.
  • Install the new catalytic converter with new gaskets.
  • Torque bolts to manufacturer's specifications (check service manual for exact values).

4. Clear Error Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Start the engine and allow it to idle, checking for any codes that may reappear.