how to fix P0420 code on Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for damage or contamination.
• Replace any faulty oxygen sensors with OEM or equivalent parts.
• Torque the new sensors to the manufacturer's specifications (usually around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust manifold gaskets
• If the catalytic converter is determined to be defective, remove it from the exhaust system.
• Disconnect any brackets or hangers securing the catalytic converter.
• Install the new catalytic converter, ensuring proper alignment with the exhaust system.
• Replace any gaskets as necessary and torque the bolts to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any stored codes from the system.

5. Test Drive

• Conduct a test drive to ensure the check engine light does not reappear and to verify overall performance.