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

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a level surface and securely supported with jack stands.
• Disconnect the battery to prevent electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:

   • Identify the upstream (before the catalytic converter) and downstream (after the catalytic converter) oxygen sensors.

2. Remove the Oxygen Sensors:

   • Use an oxygen sensor socket to carefully unscrew and remove both sensors.
   • Inspect the threads and connectors for damage.

3. Install New Oxygen Sensors:

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

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components:

   • Loosen and remove any bolts or clamps securing the exhaust system to access the catalytic converter.
   • Use penetrating oil if bolts are rusted.

2. Remove the Catalytic Converter:

   • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
   • Carefully remove the catalytic converter from its position.

3. Install New Catalytic Converter:

   • Place the new catalytic converter in position and secure it with bolts to the exhaust manifold and exhaust pipe.
   • Torque bolts to manufacturer specifications (usually around 30-40 lb-ft).

4. Reconnect Battery and Clear Codes

1. Reconnect the Battery:

   • Securely connect the battery terminal and ensure all connections are tight.

2. Clear the Codes:

   • Use the OBD-II scanner to erase the P0420 and any other related codes.

3. Test Drive:

   • Perform a test drive to ensure the check engine light does not reappear.