how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, safety gloves, safety goggles.
• Safety Warnings: Disconnect the battery before performing any repairs. Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the sensors: Use an O2 sensor socket to unscrew and remove the sensors from their locations.
3. Test the sensors: Using a multimeter, check the voltage output of the upstream sensor; it should fluctuate between 0.1 to 0.9 volts.
4. Replace faulty sensors: If any sensor is out of specification, replace it with a new one, ensuring to use anti-seize compound on the threads.

3. Inspect and Replace the Catalytic Converter

1. Locate the catalytic converter: Follow the exhaust system from the engine to find the catalytic converter.
2. Remove mounting bolts: Use a socket set to remove the bolts connecting the catalytic converter to the exhaust manifold and exhaust pipe.
3. Check for damage: Inspect the catalytic converter for physical damage or blockage.
4. Install new catalytic converter: Place the new catalytic converter in position, securing it with the bolts to the correct torque specifications (typically around 30-40 lb-ft).
5. Reconnect exhaust: Ensure all connections are tight and secure to prevent leaks.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery: After repairs, reconnect the battery terminals.
2. Clear error codes: Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Perform a test drive: Drive the vehicle under varying conditions to ensure the code does not reappear.