how to fix the P0420 code in my Skoda Octavia NFL (2020-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, gloves.
• Safety Warnings: Disconnect the battery before working on electrical systems, allow the exhaust to cool before inspection.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:
   • Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove Sensors:
   • Using a socket or wrench, carefully unscrew the sensors from the exhaust manifold and catalytic converter.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Tighten to the manufacturer's specifications (usually around 30 Nm), ensuring not to over-tighten.
4. Reconnect Electrical Connectors:
   • Plug in the new sensors securely to their respective connectors.

3. Inspect and Replace Catalytic Converter

1. Raise the Vehicle:
   • Use a jack and jack stands to lift the vehicle securely.
2. Remove Exhaust Components:
   • Disconnect the exhaust pipe from the catalytic converter using a socket set to remove bolts/clamps.
3. Remove Catalytic Converter:
   • Unscrew the mounting bolts holding the catalytic converter in place.
   • Remove the catalytic converter from the vehicle.
4. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it with mounting bolts.
   • Reattach the exhaust pipe, ensuring a tight seal.
5. Reconnect Battery:
   • Reconnect the battery terminals securely.