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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and ensure the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and disconnect the wiring harness.
  2. Use an O2 sensor socket to remove the upstream sensor.
  3. Install the new upstream oxygen sensor and tighten it to the manufacturer’s specified torque (typically around 30 lb-ft).
  4. Repeat the process for the downstream (post-catalytic) oxygen sensor.
  5. Reconnect the wiring harnesses for both sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter, jack stands, safety goggles, gloves.
• Sub-steps:
  1. Raise the vehicle securely on jack stands to access the exhaust system.
  2. Use an exhaust pipe cutter to remove the catalytic converter from the exhaust system.
  3. Inspect the old catalytic converter for signs of damage or blockage.
  4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  5. Tighten all bolts and connections to the manufacturer’s specified torque.
  6. Lower the vehicle and reconnect the battery.