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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, oxygen sensor socket, safety glasses, gloves.

2. Inspect and Replace Oxygen Sensors

• Remove the upstream oxygen sensor:
  • Use an oxygen sensor socket to carefully unscrew and remove the sensor from the exhaust manifold.
• Install new upstream oxygen sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Hand-tighten the sensor, then torque to manufacturer specifications (usually around 30 ft-lbs).
• Repeat for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Remove the catalytic converter:
  • Use a socket set to unbolt the catalytic converter from the exhaust system. Ensure to support the exhaust system to prevent damage.
• Inspect the old catalytic converter:
  • Check for any signs of physical damage, clogging, or contamination.
• Install the new catalytic converter:
  • Position the new converter and align the bolts.
  • Torque the bolts to manufacturer specifications (typically 40-50 ft-lbs).

4. Reconnect and Test

• Reconnect the battery.
• Start the engine and allow it to reach operating temperature.
• Use the OBD-II scanner to clear the trouble codes and monitor for any recurrence.