how to fix P0420 code on my Honda Accord Eleventh Generation (2023-present)?

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Disconnect the wiring harness from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust pipes.
  4. Install new oxygen sensors and torque to manufacturer specifications (typically around 30 lb-ft).
  5. Reconnect the wiring harnesses.

3. Repair or Replace Catalytic Converter

• Tools Required: Wrench set, cutting tool (if necessary), gasket scraper, high-temperature exhaust sealant.
• Sub-steps:
  1. Inspect the catalytic converter for any physical damage or clogging.
  2. If necessary, remove the catalytic converter by loosening the bolts connecting it to the exhaust system.
  3. Clean the mounting surfaces with a gasket scraper.
  4. Install a new catalytic converter, ensuring proper alignment.
  5. Torque the bolts to manufacturer specifications (generally around 25 lb-ft).
  6. Apply high-temperature exhaust sealant to any joints if required.

4. Clear the Code

• Use an OBD-II scanner to erase the P0420 code from the vehicle’s computer.
• Reconnect the battery.