how to fix the P0420 code in my Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and extension.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Using the O2 sensor socket, unscrew the upstream oxygen sensor and disconnect the wiring harness.
  3. Install the new upstream oxygen sensor and torque it to manufacturer specifications (typically around 30 lb-ft).
  4. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Wrench set, torque wrench, and exhaust pipe cutter (if needed).
• Sub-steps:
  1. Locate the catalytic converter and inspect it for physical damage or clogging.
  2. If replacement is needed, unbolt the catalytic converter from the exhaust system using the wrench set.
  3. Ensure all gaskets and seals are replaced during installation.
  4. Install the new catalytic converter and torque the bolts to manufacturer specifications (typically around 40 lb-ft).
  5. Reconnect any exhaust components removed during the process.

4. Reconnect Battery and Clear Codes

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