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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Safety goggles
• Jack and jack stands

2. Inspect and Replace O2 Sensors

1. Remove the upstream O2 sensor:
   • Locate the upstream O2 sensor on the exhaust manifold.
   • Use a socket wrench to unscrew and remove the sensor.
2. Install the new upstream O2 sensor:
   • Apply anti-seize compound to the threads of the new O2 sensor.
   • Install and tighten to the manufacturer’s specifications (usually around 30 ft-lbs).
3. Repeat for the downstream O2 sensor if faulty:
   • Locate the downstream O2 sensor behind the catalytic converter.
   • Remove and replace as described above.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Remove exhaust components:
   • Loosen and remove the bolts securing the catalytic converter to the exhaust system.
   • Carefully detach the catalytic converter from the exhaust manifold and exhaust pipe.
2. Inspect the old catalytic converter:
   • Check for signs of damage or clogging. Replace if necessary.
3. Install the new catalytic converter:
   • Position the new catalytic converter and align it with the exhaust pipes.
   • Secure with bolts and torque to the specified value (usually around 30 ft-lbs).

4. Final Checks

1. Reconnect the battery:
   • Reattach the negative battery terminal securely.
2. Clear the P0420 code:
   • Use the OBD-II scanner to clear the trouble codes from the ECU.
3. Test drive the vehicle:
   • Drive the car under various conditions to ensure the check engine light does not return.