how to troubleshoot Honda Civic 11th Generation (2022-Present) P0420 error code

Solution

1. Preparation

• Gather tools and safety equipment.
• Tools Required: OBD-II scanner, multimeter, infrared thermometer, socket set, jack stands, safety goggles, gloves.
• Safety Warning: Disconnect the battery before working on electrical systems.

2. Inspect and Replace Oxygen Sensors

• Step 1: Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Step 2: Disconnect the electrical connectors from both sensors.
• Step 3: Use a socket to remove the sensors from the exhaust manifold and exhaust pipe.
• Step 4: Install the new sensors by threading them into place and tightening to the manufacturer’s torque specifications (usually around 30-35 lb-ft).
• Step 5: Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Step 1: Raise the vehicle securely on jack stands.
• Step 2: Disconnect the exhaust pipes from the catalytic converter (if applicable), using the appropriate socket.
• Step 3: Remove any mounting bolts or brackets holding the catalytic converter in place.
• Step 4: Remove the old catalytic converter and replace it with a new one.
• Step 5: Reattach the exhaust pipes, ensuring all connections are secure and properly sealed.
• Step 6: Lower the vehicle and reconnect the battery.