Why does the Audi A4L idle shake without any fault codes?

[Malia]

Audi A4L idle shaking without any fault codes may be caused by the following reasons: Fuel quality issues: The shaking may be caused by fuel quality issues, such as using gasoline with a lower octane rating than recommended or poor-quality gasoline, which can lead to idle shaking. If this problem occurs immediately after refueling, it is most likely due to fuel quality issues. In this case, it is necessary to go to a 4S shop for inspection to see if the engine has been damaged. Spark plug issues: Worn, damaged, or faulty spark plugs can also cause idle shaking. For example, excessive carbon deposits on the spark plugs can lead to shaking, and replacing them with a new set of spark plugs will resolve the issue. Carbon deposit issues: For household cars that have been driven for a long time, carbon deposits can easily cause the engine to shake at idle. Going to a repair shop for a carbon cleaning can solve the problem.