how to fix P0420 code on Honda Accord 10th Generation (2018-2022)?

Solution

1. Preparation

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

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Exhaust backpressure gauge
• Safety glasses and gloves

2. Inspect and Replace Oxygen Sensors (if necessary)

• Sub-step 1: Identify the upstream and downstream oxygen sensors (usually located before and after the catalytic converter).
• Sub-step 2: Disconnect the electrical connectors from the oxygen sensors.
• Sub-step 3: Use the appropriate socket to remove the old oxygen sensors from the exhaust system.
• Sub-step 4: Install the new oxygen sensors, ensuring they are torqued to manufacturer specifications (typically 30-40 ft-lbs).
• Sub-step 5: Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-step 1: If the catalytic converter is found to be clogged or damaged, remove the exhaust pipes connected to it.
• Sub-step 2: Unbolt the catalytic converter from the exhaust manifold and the downstream exhaust pipe.
• Sub-step 3: Install the new catalytic converter, ensuring proper alignment.
• Sub-step 4: Torque all bolts to manufacturer specifications (usually around 30-50 ft-lbs).
• Sub-step 5: Reconnect any exhaust hangers or brackets that were removed.

4. Clear Codes and Test Drive

• Sub-step 1: Reconnect the negative terminal of the battery.
• Sub-step 2: Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Sub-step 3: Start the engine and allow it to reach operating temperature.
• Sub-step 4: Take the vehicle for a test drive to ensure that the check engine light does not reappear.