how to fix P0420 code in Honda Accord 8th Generation (2008-2012)

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: Socket set, O2 sensor socket, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate and remove the upstream oxygen sensor (usually near the exhaust manifold).
  2. Apply penetrating oil to the threads if the sensor is stuck.
  3. Use an O2 sensor socket to remove the sensor.
  4. Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
  5. Repeat the process for the downstream O2 sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter, new gaskets.
• Sub-steps:
  1. Raise the vehicle securely using jack stands.
  2. Disconnect the exhaust pipes from the catalytic converter using an exhaust pipe cutter if necessary.
  3. Remove the bolts securing the catalytic converter to the exhaust manifold and exhaust pipe.
  4. Install the new catalytic converter with new gaskets, ensuring a proper seal.
  5. Reconnect the exhaust pipes and torque the bolts to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the negative terminal of the battery.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.