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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket or a wrench to carefully unscrew the sensor from the exhaust manifold.
   • Inspect the sensor for carbon buildup or damage.
3. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Screw it into place and tighten to the manufacturer’s specifications (typically around 30 Nm).
4. Repeat the removal and installation process for the downstream oxygen sensor.

3. Check and Replace the Catalytic Converter (if necessary)

1. Inspect the catalytic converter: If the oxygen sensors are functioning properly, check the catalytic converter for blockages or internal damage.
2. Remove the catalytic converter:
   • Support the exhaust system using jack stands.
   • Unbolt the catalytic converter from the exhaust pipe and exhaust manifold, using a socket set.
3. Install the new catalytic converter:
   • Position the new catalytic converter and align it with the exhaust system.
   • Bolt it into place, ensuring all gaskets are replaced and properly sealed.
   • Torque the fasteners to the manufacturer’s specifications.

4. Clear Error Codes

1. Reconnect the negative terminal of the battery.
2. Use the OBD-II scanner to clear the P0420 code.