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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to avoid any electrical shorts.
• Raise the vehicle using a jack and secure it on jack stands for safe access to the undercarriage.

2. Inspect and Replace the Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Disconnect the electrical connector from the sensor.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
• Install the new upstream O2 sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Hand-tighten the sensor into the manifold and then torque to the manufacturer's specification (typically 30-40 ft-lbs).
  3. Reconnect the electrical connector.
• Repeat the process for the downstream (post-catalytic) oxygen sensor if necessary.

3. Inspect the Catalytic Converter

• Tools Required: Wrench set, exhaust pipe cutter, or sawzall (if replacement is needed).
• Check the catalytic converter for damage:
  1. Look for dents, cracks, or rust.
  2. Tap the converter lightly; listen for rattling sounds indicating internal damage.
• If the catalytic converter is damaged, replace it:
  1. Cut the exhaust pipes leading to and from the catalytic converter using an exhaust pipe cutter.
  2. Install the new catalytic converter using new gaskets and clamps.
  3. Ensure all connections are secure and torqued to specifications.

4. Clear Error Codes

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