how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Using an O2 sensor socket, remove the upstream oxygen sensor.
  3. Install the new upstream oxygen sensor and torque it to the manufacturer's specifications (usually around 30-40 ft-lbs).
  4. Repeat the process for the downstream oxygen sensor if deemed faulty.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove the exhaust pipes connected to the catalytic converter using a socket set.
  2. Unbolt the catalytic converter from the exhaust manifold.
  3. Inspect the old catalytic converter for signs of blockage or damage.
  4. Install the new catalytic converter, ensuring proper alignment and secure it with bolts to the exhaust manifold.
  5. Reattach the exhaust pipes and secure them with clamps.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear any stored codes.
  3. Start the engine and allow it to reach operating temperature.
  4. Perform a test drive under various conditions to ensure the code does not return.