Multiple RS4 System Errors Point to Electrical Issue

Having some experience working on performance cars, I faced a similar situation with my 2010 RS5 last year. Multiple system errors appeared simultaneously, triggering the malfunction indicator light and several warning messages. Initially, my basic OBD-II scanner also showed multiple fault codes across different systems. After some research, I took it to a specialized workshop where they used an advanced diagnostic scanner to identify that the root cause was incorrect vehicle coding after a previous software update. The fix involved recoding the vehicle control modules and clearing all fault codes. Total cost was 360 Euro for diagnostic work and coding. The issue hasnt returned since the repair. Before suggesting specific solutions for your case, could you share: Have there been any recent repairs or software updates? Which specific error messages are you seeing? Are there any noticeable performance issues while driving? What fault codes did your scan tool reveal? A professional scan with a complete diagnostic tool would help identify if your issue is also coding-related or stems from a different root cause.

Last service was at 16260KM and they found no issues during inspection. The fault codes from my basic scan tool point toward something electrical rather than mechanical, which matches with the multiple system errors showing up at once. Interestingly, the check engine light sometimes goes off after restarting the car, but the other warning messages remain. I havent had any repairs or updates done recently, and performance feels normal while driving. The errors shown are mostly related to sensor inputs and communication between control modules. Getting an advanced diagnostic scan makes sense as the next step.

Thanks for sharing those details. Your symptoms sound even more similar to what I experienced with my RS5 now that you mention the check engine light behavior and normal performance. The intermittent check engine light combined with persistent warning messages strongly suggests a communication issue between control modules, much like my case. Using a basic OBD-II scanner was helpful for initial diagnosis, but the advanced diagnostic scanner at the workshop revealed the full scope of the issue. The fault codes related to sensor inputs and module communication match the pattern I saw before my repair. One thing I learned from my experience: while the car drives normally now, these types of electrical system errors can eventually affect other modules if left unaddressed. The fact that your check engine light resets after restart but other warnings persist is a classic sign of a control module communication problem. Since your service history shows no recent work and the issue appeared spontaneously, Id recommend going straight for a professional diagnostic scan. They can reset codes properly and check module coding to prevent future issues. The repair cost might be similar to what I paid (360 Euro), assuming its the same root cause. Would be interested to hear what they find when you get it checked. These electrical gremlins can be tricky to diagnose without proper diagnostic equipment.

Thanks for the detailed feedback. The electrical/communication nature of the problem seems most likely given how the warnings behave. Getting an advanced engine diagnostic scan is my next step, especially since my basic scan tool shows sensor and module communication codes. The fact that similar issues were resolved through control module recoding for around 360 Euro is encouraging, much better than potentially facing major mechanical repairs. While the car drives fine now, I agree its best to address these electrical gremlins before they potentially cascade into other systems. I'll book an appointment with a workshop that has proper diagnostic equipment. Since the check engine light comes and goes but other warnings persist, having them do a complete system scan and proper fault code reset makes sense. Will update once I know the root cause and repair cost.