Honda Accord Eleventh Generation (2023-present) P0420 code, what does it mean?

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Using the O2 sensor socket, remove the upstream oxygen sensor.
  3. Install the new upstream oxygen sensor and torque to manufacturer specifications (usually around 30-40 lb-ft).
  4. Repeat for the downstream oxygen sensor if needed.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary), gasket scraper.
• Sub-steps:
  1. Remove any heat shields or brackets securing the catalytic converter.
  2. Use an exhaust pipe cutter to carefully cut the exhaust pipe if necessary.
  3. Remove the old catalytic converter from the exhaust system.
  4. Clean the mating surfaces on the exhaust pipe and exhaust manifold.
  5. Install the new catalytic converter, ensuring proper alignment.
  6. Torque all bolts to manufacturer specifications and reattach any heat shields.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.