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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical issues.
• Allow the vehicle to cool down before working on the exhaust system.

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 oxygen sensor socket or wrench to carefully unscrew each sensor from the exhaust manifold and catalytic converter. Avoid damaging the wiring.
3. Inspect the sensors: Check the sensors for carbon buildup or damage. If they appear faulty, replace them.
4. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them securely. Torque them to the manufacturer’s specifications.

3. Examine and Replace the Catalytic Converter (if necessary)

1. Inspect the catalytic converter: Check for physical damage, rattling, or excessive heat discoloration.
2. Remove the old catalytic converter: Unbolt it from the exhaust system using a socket set. You may need to cut pipes if they are rusted together.
3. Install the new catalytic converter: Position the new converter in place and secure it with bolts. Ensure to use new gaskets if required. Torque bolts to specifications.
4. Reinstall any removed exhaust components: Reattach any parts that were removed to access the catalytic converter.

4. Clear Codes and Test Drive

1. Reconnect the battery: Reconnect the negative terminal and ensure all connections are secure.
2. Clear the codes: Use the OBD-II scanner to erase the P0420 code from the vehicle's memory.
3. Test drive the vehicle: Drive the car under various conditions to monitor the performance and ensure the check engine light does not reappear.