RS3 Starting Issues Point to Faulty Ignition Switch

Had the exact same starting issue with my 2014 S3 last winter. Have some experience working on these engines but still rely on professional help for electrical problems. The symptoms match what I experienced, unreliable starting and rough running. Initially thought it was the ignition coil or starter motor, but my workshop diagnosed a blown fuse in the main ignition circuit. The dashboard lights would come on, but the ignition key would not engage the starter properly. The repair was straightforward once diagnosed, just needed the fuse replaced and the surrounding connections cleaned. Total cost was 52 Euro including labor and parts. The car has been running perfectly since then. Before jumping to conclusions though, would need to know: Are there any warning lights on the dashboard? Does the engine crank when you turn the key? Have you noticed any electrical issues with other systems? Does it happen more often when the engine is cold or warm? What is the current mileage on your RS3? These details would help determine if your issue is similar or potentially something else.

Thanks for sharing those details. My RS3 currently shows 194967 KM and had its last service about 3 months ago. These symptoms started appearing right after that service, actually. The starter motor does crank, but very weakly. No warning lights appear on the dashboard before the starting issue occurs. The problem definitely happens more when the engine is cold, especially in the morning. The ignition switch feels a bit loose when turning the key, which makes me think it might be more than just a fuse in my case. Interesting that you mention the fuse, will definitely have that checked first since its the cheapest potential fix. Did your mechanic mention any other common failure points in the ignition system that could cause similar symptoms?

Thanks for those extra details about your RS3. The symptoms you describe are actually quite different from my fuse issue, especially with that loose ignition key feel and weak cranking. After fixing my fuse problem, my mechanic explained that weak cranking combined with a loose ignition switch often points to worn ignition switch contacts or a failing starter motor. Given your high mileage and the fact it started after the service, there might be multiple issues at play. In my S3, after the initial fuse fix, I actually ended up having to replace the starter motor about 6 months later when similar symptoms returned. The starter motor replacement cost around 380 Euro including labor. The mechanic showed me how the old starter had worn brushes that were causing inconsistent contact. The cold start issues you mention are particularly telling, my mechanic explained that worn starter motors often struggle most during cold starts due to increased resistance. The fact your dashboard lights work normally suggests the main electrical system is okay, but the ignition switch and starter motor should definitely be inspected. Would suggest getting both the ignition switch and starter motor tested, the workshop can do this with specialized diagnostic equipment to pinpoint exactly which component is failing.

Thanks for the input. Given the different symptoms between my case and yours, I will definitely have both the starter motor and ignition switch checked professionally. The cold start issues and loose key turning really point toward something more serious than just a blown fuse. Just booked an appointment with my workshop for next week. Will have them run a full diagnostic on the car electronics and starting system. While the 380 Euro cost reference for a starter motor replacement is helpful to know, I am preparing for potentially higher costs if both components need replacing. The car is still driveable, but I will avoid any long trips until this is resolved. Will update once I get the official diagnosis and repair completed. Really hoping its just the starter motor and not a more complex ignition system problem.