my Skoda Octavia NFL (2020-Present) has a rough idle, especially when cold, what's wrong?

Solution

1. Preparation

• Gather all necessary tools and parts before beginning.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plugs

• Remove the spark plug cover using a socket wrench.
• Use a spark plug socket to remove the spark plugs.
• Inspect the spark plugs for wear or carbon buildup.
• If worn, replace with OEM or high-quality aftermarket spark plugs with specified gap (usually 0.8mm for Skoda).
• Reinstall the spark plugs and tighten to manufacturer torque specifications (typically around 25 Nm).

3. Clean or Replace the Idle Air Control Valve (IAC)

• Locate the IAC valve, typically near the throttle body.
• Disconnect the electrical connector and remove the valve using a socket set.
• Clean the valve with throttle body cleaner if reusable; otherwise, install a new IAC valve.
• Reconnect the electrical connector.

4. Check and Replace Engine Coolant Temperature Sensor

• Locate the engine coolant temperature sensor (usually near the thermostat housing).
• Disconnect the wiring harness and remove the sensor using a socket or wrench.
• Install the new sensor and reconnect the wiring harness.
• Make sure to top off the coolant if necessary.

5. Fuel System Inspection

• Connect a fuel pressure gauge to the fuel rail.
• Start the engine and read the fuel pressure; it should be within the manufacturer’s specifications (typically 3-4 bar).
• If pressure is low, inspect the fuel filter, fuel pump, and injectors for issues.
• Replace the fuel filter if it has not been changed recently.

6. Final Steps

• Reconnect the battery.
• Start the engine and allow it to reach operating temperature.
• Monitor for any error codes or symptoms during this process.