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

• Step 1: Locate the upstream and downstream oxygen sensors on the exhaust system.
• Step 2: Unplug the electrical connectors from the oxygen sensors.
• Step 3: Using a socket wrench, remove the oxygen sensors from their respective locations.
• Step 4: Install the new oxygen sensors, ensuring they are properly torqued to the manufacturer's specifications (usually around 30 lb-ft).
• Step 5: Reconnect the electrical connectors securely.

3. Examine and Replace Catalytic Converter

• Step 1: If the catalytic converter is suspected to be faulty, remove the exhaust system components leading to it, such as heat shields or mounting brackets.
• Step 2: Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
• Step 3: Inspect the old catalytic converter for blockages or damage.
• Step 4: Install the new catalytic converter, ensuring all bolts are torqued to specifications (typically around 35 lb-ft).
• Step 5: Reattach any components removed previously, ensuring a secure fit.

4. Clear Codes and Test Drive

• Step 1: Reconnect the battery.
• Step 2: Use the OBD-II scanner to clear the P0420 code.
• Step 3: Start the engine and perform a test drive to ensure proper operation.