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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Locate the upstream (pre-catalytic) oxygen sensor.
   • Use an O2 sensor socket to unscrew and remove it.
2. Install the new oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Install the new sensor and tighten to the manufacturer's specifications (usually around 30 Nm).

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

1. Remove the catalytic converter:
   • Unbolt the catalytic converter from the exhaust system using a socket set.
   • Carefully detach any heat shields if they obstruct the removal.
2. Install the new catalytic converter:
   • Position the new catalytic converter in place.
   • Bolt it securely, ensuring to follow the manufacturer's torque specifications (typically around 45 Nm).

4. Reconnect Sensors and Battery

• Reconnect the downstream oxygen sensor following the same procedure as the upstream.
• Reconnect the negative battery terminal.

5. Reset the Engine Control Unit (ECU)

• Use the OBD-II scanner to clear the P0420 code from the ECU.
• Perform a test drive to allow the ECU to re-evaluate the catalytic converter efficiency.