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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Locate the sensor in the exhaust manifold or downpipe.
  2. Use the O2 sensor socket to unscrew it.
  3. Install the new sensor and torque to manufacturer specifications (usually around 30 Nm).
• Repeat for the downstream (post-catalytic) oxygen sensor if testing indicates it is faulty.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the catalytic converter:
  1. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  2. Use the exhaust hanger removal tool to detach it from the rubber hangers.
  3. Inspect the old catalytic converter for signs of clogging or damage.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque all bolts to manufacturer specifications (typically between 25-35 Nm).

4. Reassemble and Test

• Reconnect the battery.
• Clear the error codes using the OBD-II scanner.
• Start the engine and let it idle for a few minutes to check for leaks.