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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

1. Remove the O2 Sensors:

   • Locate the upstream and downstream oxygen sensors.
   • Use an oxygen sensor socket to carefully unscrew and remove the sensors from the exhaust manifold and catalytic converter.
   • Tools Required: Oxygen sensor socket, wrench.

2. Inspect Sensors:

   • Examine the sensors for signs of damage or excessive carbon buildup.

3. Install New Sensors:

   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and torque to manufacturer specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

1. Remove the Exhaust Components:

   • Unbolt the exhaust pipes connected to the catalytic converter using a socket set.
   • Remove any brackets or hangers securing the exhaust to the vehicle.
   • Tools Required: Socket set, penetrating oil (if rusted).

2. Remove the Catalytic Converter:

   • Take out the old catalytic converter from its position.
   • Inspect the exhaust manifold for any obstructions or damage.

3. Install New Catalytic Converter:

   • Position the new catalytic converter in place.
   • Reattach the exhaust components, ensuring all bolts are tightened to manufacturer specifications.
   • Tools Required: Torque wrench, gasket sealant (if needed).

4. Reconnect Battery

• Reconnect the battery terminals securely.

5. Clear Codes and Test Drive

• Use the OBD-II scanner to clear any stored codes and test drive the vehicle to ensure the check engine light does not reappear.