how to fix P0420 code in Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent any electrical issues.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor using the O2 sensor socket.
• Inspect the sensor for damage or contamination, replace it if necessary.
• Install the new oxygen sensor and torque to manufacturer specifications (typically around 33 lb-ft).
• Repeat the process for the downstream oxygen sensor if indicated by diagnostics.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter, torque wrench, gasket scraper
• Remove the bolts securing the exhaust pipe to the catalytic converter using the socket set.
• Cut the exhaust pipe if it is too corroded to remove normally.
• Remove the catalytic converter and inspect the mounting surface for any debris or old gasket material.
• Install the new catalytic converter, ensuring proper alignment with the exhaust system.
• Reinstall the exhaust pipe and torque the bolts to the manufacturer specifications.

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to verify that the check engine light does not reappear.