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

Solution

1. Preparation

• Disconnect the vehicle's battery to prevent electrical shorts during repair.
• Gather necessary tools and parts.
• Raise the vehicle using a hydraulic jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Disconnect the wiring harness from each sensor.
3. Use an oxygen sensor socket to remove the old sensors.
4. Apply anti-seize compound to the threads of the new sensors.
5. Install the new sensors and reconnect the wiring harness.

3. Inspect and Replace the Catalytic Converter

1. Remove the exhaust heat shield if applicable.
2. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe using a socket set.
3. Inspect the gasket surfaces for damage and clean if necessary.
4. Install the new catalytic converter, ensuring proper alignment.
5. Torque the bolts to the manufacturer's specifications (typically around 40-50 lb-ft).
6. Reattach the exhaust heat shield if removed.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery terminals ensuring a secure connection.
2. Use the OBD-II scanner to clear the P0420 code from the ECM.