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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts during the repair.

2. Replace Faulty Oxygen Sensors (if needed)

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Disconnect the electrical connectors from each oxygen sensor.
3. Use an oxygen sensor socket to remove the sensors from their respective locations.
4. Install the new oxygen sensors by screwing them into place and tightening them to the specified torque (usually around 30-40 ft-lbs).
5. Reconnect the electrical connectors to the new sensors.

3. Inspect and Replace the Catalytic Converter (if needed)

1. Remove the exhaust heat shield if applicable to access the catalytic converter.
2. Unbolt the catalytic converter from the exhaust manifold and the mid-pipe using a socket set.
   • Note: Use penetrating oil on rusty bolts if necessary.
3. Remove the catalytic converter and inspect for any blockage or damage.
4. Install the new catalytic converter, ensuring proper alignment.
5. Bolt the catalytic converter back to the exhaust manifold and mid-pipe, tightening to manufacturer's specifications (usually around 25-30 ft-lbs).
6. Reinstall the exhaust heat shield if removed.

4. Reset the Check Engine Light

1. Reconnect the negative battery terminal.
2. Use an OBD-II scanner to clear the P0420 code from the system.