RS5 Electrical Gremlins: Nav Dead & Multiple Failures

Just went through something very similar with my 2021 RS4. As someone with some experience working on these cars, I can share that modern vehicles heavily depend on properly functioning control units and their software. The symptoms you describe match what I experienced, multiple electrical issues and a dead navigation system pointed toward a software malfunction in the main control unit. My workshop diagnosed it as corrupted software that required a complete recalibration and software update of the control unit. The fix cost me 240 Euro and took about half a day at the workshop. Since the update, everything has been working flawlessly. The technician explained that these issues sometimes occur when the control unit loses sync with other vehicle systems. Before suggesting more specific solutions, could you share: Any specific error codes shown by your onboard diagnostics? Did these issues appear suddenly or gradually? Have you had any recent battery issues or electrical work done? Are there any other electrical systems affected besides navigation? This information would help determine if your case is similar and whether the same solution might work for you.

Latest service was at 85000 KM. I got the ECU problem codes P0705 and P0706 from the onboard diagnostics system showing up suddenly last week. No recent battery problems or electrical work. Besides the navigation, the climate control now acts weird, out of nowhere switching between different temperature settings. The blind spot monitoring system is also inconsistent, sometimes working and sometimes not. Unfortunately, this sounds like it might be more complex than just a software reset. Looking at 240 Euro for diagnostics alone seems reasonable given these multiple system failures. Will definitely get it checked at the workshop soon and report back on their findings.

I experienced nearly identical issues with my RS4, those exact ECU problem codes (P0705/P0706) along with the erratic climate control and blind spot monitoring problems. Initially, I also thought a simple software reset might fix it, but the multiple system failures pointed to a deeper control module issue. My case turned out to be more complex than the initial software update I mentioned. The workshop found that the main control module had partially failed, causing these cascading software-related issues across multiple systems. The full fix involved: Complete ECU diagnostic scan, Hardware replacement of the faulty control module, Vehicle software update and system recalibration, Full system testing to ensure all functions were restored Total repair cost came to 1850 Euro and took 3 days, significantly more than my initial software-only fix. However, all systems have been working perfectly for the past 6 months with no recurrence of the software bug or electrical issues. Given the similarity of your symptoms and error codes to my experience, I would recommend preparing for a potential control module replacement rather than just a software reset. The workshop should be able to confirm this with their diagnostic tools.

Based on those responses, I should conclude the conversation from's perspective: Thanks for the detailed insight into your similar experience. Those repair details and timeline are really helpful for setting my expectations. The fault patterns do sound identical to what you went through, so I will prepare for the possibility of a full control module replacement and software update rather than just a basic reset. The 1850 Euro cost estimate helps with budgeting, even though I hope it ends up being just a software issue. Good to hear your systems have stayed stable for 6 months after the fix. I have scheduled a workshop appointment for next week to get the ECU problems diagnosed properly. Will update the forum once I know the exact cause and repair outcome in case it helps others with similar control unit failures.