how to fix P0420 code on my Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down before starting work on the exhaust system.

2. Oxygen Sensor Replacement (if faulty)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor:
  1. Locate the upstream oxygen sensor near the exhaust manifold.
  2. Use the O2 sensor socket to unscrew the sensor carefully.
  3. Disconnect the wiring harness from the sensor.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Connect the wiring harness to the new sensor.
  3. Torque the sensor to the manufacturer's specification (usually around 30 ft-lbs).

3. Catalytic Converter Inspection and Replacement (if necessary)

• Tools Required: Socket set, torque wrench, exhaust sealant
• Inspect the catalytic converter:
  1. Check for any signs of physical damage, rust, or blockage.
  2. If damaged or blocked, the catalytic converter must be replaced.
• Remove the old catalytic converter:
  1. Loosen and remove the bolts connecting the catalytic converter to the exhaust pipes.
  2. Carefully remove the converter from its mounting brackets.
• Install the new catalytic converter:
  1. Position the new converter in place.
  2. Reattach using new bolts and gaskets if necessary, torquing to specifications (check manufacturer guidelines).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory.