Audi A6 ABS Light: Speed Sensor Issues Explained

As someone with moderate experience working on Audis, I dealt with a similar issue on my 2015 A7. The symptoms you describe match exactly what I experienced, constant ABS light and no traction control, despite a working speedometer. The malfunction turned out to be a defective control unit that was misinterpreting the wheel sensor input signals. Initially, I thought it was just faulty sensors, but the dashboard warnings persisted even after cleaning the sensors. The workshop diagnosed it as a failed ABS control module that needed replacement. The repair cost me 1000 Euro including programming and calibration. Since then, all systems have worked flawlessly with no warning lights. To help diagnose your specific case more accurately, could you share: Current odometer reading, Whether the issue appeared suddenly or gradually, If you notice any other warning lights or unusual behavior, Whether you recently had any work done on the braking system, If you can feel any ABS pulsing when braking hard These details would help determine if you are facing the same control unit issue I had or if it might be something else.

Thanks for the insight. My A6 has 187873 KM on the clock with the last service done 2 months ago. The ABS issue started suddenly after driving through heavy rain. Had the input sensors cleaned but no change. The car drives fine otherwise and brakes work normally, just no ABS pulse during hard braking. The transmission also seems unaffected despite the traction control being offline. Starting to think its the control module like in your case rather than just a sensor problem. Guess I should prepare for a similar repair cost.

Good to hear back from you about your A6. After my own experience with this exact issue, I am even more convinced we are dealing with the same ABS control module failure. The fact that it started after driving through heavy rain matches the typical failure pattern, moisture intrusion can trigger these malfunctions in the control unit. Like your case, my speedometer and basic brake function remained normal, but the ECM stopped properly processing the wheel speed signals, leading to the ABS and traction system shutdown. The absence of ABS pulsing during hard braking was also identical to what I experienced. The clean sensors not resolving the malfunction further supports the control module diagnosis. In my repair, the workshop confirmed moisture damage to the module's internal components was causing incorrect signal processing. Your high odometer reading is actually typical for when these failures occur, mine happened around 165000 KM. The 1000 Euro repair cost I mentioned earlier should be fairly accurate for your situation, as the parts and labor requirements would be virtually identical. Would recommend having the control module tested and replaced soon, as driving without ABS and traction control increases risk, especially in wet conditions.

Thanks everyone for the responses. Good to get confirmation about the likely ABS control module issue. After comparing the symptoms, I think my ECM is definitely misinterpreting those wheel sensor input signals just like the other cases described. The malfunction appearing after rain exposure and the high odometer reading fits the pattern too. I will schedule the repair next week and budget around 1000 Euro for the module replacement and programming. Better to fix it properly than keep driving without proper ABS and traction control. The initial sensor cleaning was worth trying, but now I am confident the control unit itself needs replacement. Will update once the work is done in case anyone else runs into similar symptoms in the future. The details shared here about moisture-related failures and diagnostic signs will definitely help others troubleshoot these issues.