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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repair.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Test Oxygen Sensors

• Remove the oxygen sensors: Use an oxygen sensor socket to carefully unscrew the upstream and downstream sensors from the exhaust system.
• Test the sensors: Connect a multimeter to the sensor terminals and measure the voltage output while the engine is running. The upstream sensor should fluctuate between 0.1 to 0.9 volts.
• Replace faulty sensors: If either sensor is not functioning within specifications, replace them with OEM equivalent sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Remove the catalytic converter: Unbolt the catalytic converter from the exhaust system using a socket set. Be cautious of any exhaust hangers that may need to be removed.
• Inspect the converter: Check for physical damage, clogging, or excessive carbon build-up. If damaged, proceed with replacement.
• Install a new catalytic converter: Position the new converter in place and secure it with the bolts, ensuring proper alignment with the exhaust system.
• Torque specifications: Refer to the vehicle’s service manual for the correct torque values for fastening the catalytic converter.

4. Reassemble and Reconnect

• Reinstall the oxygen sensors into the new catalytic converter (if replaced) and torque to specifications.
• Reattach any exhaust hangers or brackets removed during disassembly.
• Reconnect the vehicle's battery.