how to diagnose P0420 code in Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Repair Exhaust Leaks

• Inspect all exhaust joints and gaskets.
• Tighten or replace any loose or damaged components.
• Use exhaust sealant if necessary to ensure a proper seal.

3. Replace Faulty O2 Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Remove the upstream O2 sensor from the exhaust manifold by turning it counterclockwise.
• Install the new O2 sensor and torque it to the manufacturer's specification (typically around 30-40 lb-ft).
• Repeat the process for the downstream O2 sensor if necessary.

4. Replace Catalytic Converter (if needed)

• Tools Required: Socket set, cutting tools (if necessary), and exhaust hanger removal tool.
• Remove the exhaust pipe connected to the catalytic converter by unbolting it from the flanges.
• Remove the catalytic converter from its mountings.
• Install the new catalytic converter, ensuring it is properly aligned and secured.
• Reattach the exhaust pipe and ensure all connections are tight.

5. Reconnect Battery

• Reconnect the negative battery terminal and ensure a secure connection.

6. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code and any other related codes from the vehicle's computer.