my Volkswagen Passat B8 (2015-2022) has rough idle when I start it

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge, cleaning supplies.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Address Check Engine Codes

• Connect the OBD-II scanner to the vehicle's diagnostic port.
• Record any trouble codes and investigate them to identify specific issues.
• Clear the codes after making repairs.

3. Inspect and Replace Spark Plugs

• Remove the engine cover if necessary.
• Use the socket set to remove the spark plugs; inspect for wear and carbon buildup.
• Replace with new spark plugs that meet manufacturer specifications.
• Torque the new spark plugs to the recommended specification (typically around 15-20 Nm).

4. Clean the Throttle Body

• Remove the air intake duct to access the throttle body.
• Use throttle body cleaner and a soft cloth to clean the throttle plate and bore.
• Reassemble the air intake duct, ensuring all clamps are secured.

5. Fuel System Inspection

• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition on (do not start) and check the fuel pressure; it should meet manufacturer specifications.
• If pressure is low, inspect the fuel pump and filter for clogs or failure; replace as needed.