Audi ABS Warning Points to Speed Sensor Malfunction

Had a similar issue with my 2013 Audi S3. Started with ABS warnings and unstable braking, which made driving pretty nerve-wracking. As someone with some experience working on cars, I first thought it was just a sensor issue. The diagnostic scan showed multiple error codes related to the speedometer and ABS system. After a few attempts to reset the system, it became clear the ECM was getting faulty speed input signals. Took it to a workshop specializing in transmission and electrical systems. They found the control unit was completely defective and needed replacement. The repair involved: Full system diagnostic, Replacing the ABS control unit, Recoding and calibrating the new unit, Testing all speed sensors Total cost came to 1000 Euro. Not cheap, but the car has been running perfectly since the fix, with no more warning lights or stability issues. To provide more specific advice about your S1, could you share: Current mileage, When the problem first started, Whether the warning lights are constant or intermittent, If you notice the issues more in specific weather conditions, Any recent repairs or modifications

My mileage is currently at 72291 KM. Got it serviced right before these ABS warning lights started appearing on the dashboard. The speedometer readings seem inconsistent at times, which aligns with what you mentioned about faulty speed input signals. The malfunction warning is pretty much constant now, not intermittent like it was in the beginning. The ABS issue happens regardless of weather conditions, so I suspect its more of a system fault rather than environmental factors. The braking instability is really concerning, especially at higher speeds. Thanks for sharing your repair experience, helps to know what kind of costs I might be looking at. Will probably need to get it checked by a specialist workshop rather than trying any quick fixes.

Just wanted to follow up since our ABS issues were so similar. After seeing your description about the inconsistent speedometer readings, it definitely sounds like the same problem I faced with my S3. The constant warning lights and speed signal input problems are classic signs of a failing ABS control module. One thing I forgot to mention in my earlier post, before the complete ABS control unit replacement, the dashboard would sometimes show incorrect speed readings, which matches what you are experiencing. The ECM was getting corrupted data from the failing sensor inputs. The braking instability you are noticing at higher speeds is exactly what I dealt with. Its not safe to keep driving like this since the ABS system cant properly modulate brake pressure without accurate speed signals. Since your mileage is in a similar range to when my issues started, and the symptoms are almost identical, Id strongly suggest getting the full diagnostic done soon. The 1000 Euro repair cost I mentioned included programming, but prices might have changed since then. The good news is that once the control unit was replaced, all these issues, unstable braking, faulty speed readings, and constant warning lights, completely resolved.

Based on your odometer reading and insights, this really helps narrow things down. The faulty speedometer readings combined with the constant dashboard warnings definitely point to the ABS control module issue you mentioned. The sensor malfunction showing up right after servicing makes me think something might have been disturbed during maintenance. But given the similar symptoms with your S3 case, especially the ECM getting bad speed data, it does sound like the control unit is the culprit. Have contacted a workshop that specializes in ABS systems and booked the car in next week. The 1000 Euro estimate gives me a good reference point for the repair costs. The fact that your fix resolved all the stability and warning light issues is reassuring. Will skip any quick fixes since this seems too critical for trial and error. Rather get it properly diagnosed and fixed given how the braking performance is affected. Thanks again for the detailed breakdown of your experience, helped me understand what Im likely dealing with.