how to fix the P0420 code on my Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical issues while working on the vehicle.
• Raise the vehicle and secure it on jack stands for access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil (if necessary)

• Remove the upstream oxygen sensor (before the catalytic converter) by using the O2 sensor socket.

  • If it's stuck, apply penetrating oil and allow it to soak before attempting removal.

• Install the new upstream oxygen sensor and torque it to the manufacturer's specifications (typically 30-40 lb-ft).

• Repeat the process for the downstream oxygen sensor (after the catalytic converter) if it has also shown signs of malfunction.

3. Inspect and Replace the Catalytic Converter

• Parts Required: New catalytic converter (ensure it meets OEM specifications)
• Remove the bolts or clamps securing the catalytic converter to the exhaust system.
• Carefully detach the old catalytic converter from the exhaust pipe and exhaust manifold.
• Install the new catalytic converter by reversing the removal process, ensuring that all bolts are tightened to the recommended torque specifications.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
• Conduct a test drive under various conditions to confirm that the check engine light does not reappear.