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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use penetrating oil to loosen the sensors if they are difficult to remove.
  3. Disconnect the electrical connectors from both sensors.
  4. Remove the upstream sensor using the O2 sensor socket and replace it with a new one. Torque to manufacturer's specifications (typically around 30 lb-ft).
  5. Repeat for the downstream sensor if needed.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket, jack stands
• Sub-steps:
  1. Safely lift the vehicle and secure it with jack stands.
  2. Remove the exhaust pipes connected to the catalytic converter using the socket set.
  3. Inspect the catalytic converter for signs of damage or clogging.
  4. If replacement is necessary, remove the old catalytic converter and install the new one, ensuring proper alignment and sealing.
  5. Torque all bolts to the manufacturer's specifications (typically around 25 lb-ft) and replace any gaskets as needed.

4. Reset the Engine Control Module (ECM)

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