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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the vehicle’s battery to ensure safety.

2. Inspect Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter, socket set.
• Remove the upstream (pre-catalytic) oxygen sensor and inspect for contamination or damage.
• If necessary, replace the upstream oxygen sensor with a new one (OEM recommended).
• Reinstall the oxygen sensor and reconnect the electrical connector.

3. Check Catalytic Converter

• Tools Required: Exhaust jack, socket set, torque wrench.
• Raise the vehicle and support it securely on jack stands.
• Visually inspect the catalytic converter for any physical damage or signs of clogging.
• If replacement is necessary, remove the catalytic converter by loosening the bolts at the flanges.
• Install a new catalytic converter, ensuring proper alignment and torque specifications (typically 30-40 Nm).

4. Reset the Engine Control Module (ECM)

• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Reconnect the vehicle’s battery.

5. Test Drive

• Conduct a test drive to ensure the vehicle operates normally and the check engine light does not reappear.