how to troubleshoot P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery for safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream (pre-catalytic converter) oxygen sensor using the O2 sensor socket.
• Inspect the sensor for any signs of damage or contamination.
• Install a new oxygen sensor, tightening to the manufacturer's specified torque (typically around 30 lb-ft).
• Repeat the process for the downstream (post-catalytic converter) oxygen sensor if needed.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, cutting tool (if necessary), gaskets
• Remove any heat shields covering the catalytic converter if applicable.
• Disconnect the exhaust pipes from the catalytic converter, using a socket set.
• Inspect the catalytic converter for blockages or excessive wear. If damaged, replace it.
• Install the new catalytic converter, ensuring to use new gaskets and torque the bolts to manufacturer specifications.

4. Clear Codes and Test Drive

• Reconnect the battery and use a scan tool to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive under various driving conditions to ensure the check engine light does not reappear and performance is restored.