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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is turned off.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet and extensions, torque wrench.
• 1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• 1. Disconnect the wiring harness from both oxygen sensors.
• 1. Use an O2 sensor socket to remove the upstream sensor first, followed by the downstream sensor.
• 1. Install the new sensors by threading them into place and tightening them to manufacturer specifications (typically around 30 ft-lbs).
• 1. Reconnect the wiring harness to the respective sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust clamp tool, penetrating oil.
• 1. Inspect the catalytic converter for any signs of physical damage or clogging.
• 1. If replacement is needed, remove any heat shields or brackets securing the catalytic converter.
• 1. Use penetrating oil on exhaust bolts to ease removal and detach the old catalytic converter from the exhaust system.
• 1. Install the new catalytic converter, ensuring it is properly aligned and secured with clamps or bolts as per manufacturer specifications.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• 1. Reconnect the battery.
• 1. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• 1. Start the engine and allow it to reach operating temperature.
• 1. Perform a test drive to ensure the check engine light remains off and monitor performance.