E-tron ABS Warning + Speed Sensor Failure Alert

I had similar symptoms with my 2019 Audi e-tron 55 quattro when the wheel speed sensor started malfunctioning. The ABS warning light was triggered by incorrect input signals reaching the ECM, causing instability in the traction control system. The initial diagnostic revealed multiple error codes related to the ABS sensor network. A faulty speed sensor was sending erratic signals, confusing the control unit. The real problem turned out to be more complex, corrosion had damaged the wiring harness connecting the sensor to the ECM. The fix required replacing both the sensor and the affected wiring harness. This was a serious repair as the ABS system is crucial for vehicle safety. The job involved removing parts of the wheel well lining to access the damaged components and recalibrating the new sensor to ensure proper communication with the control unit. Since the repair, the ABS system has functioned flawlessly. Would strongly recommend having a certified technician perform a complete diagnostic of the ABS system, as temporary fixes might lead to more severe issues down the road.

Thanks for sharing your experience with the speed sensor malfunction. It sounds very similar to what I am dealing with on my Q4. The erratic speedometer readings and dashboard warnings are quite concerning. Did you remember the repair costs for the sensor and wiring harness replacement? Also curious if your odometer readings stayed accurate after the fix or if you noticed any other transmission-related issues popping up since then? My local shop quoted me a pretty high price so trying to get a sense if it is in line with what others paid.

After getting the speed signal fault fixed at the certified shop, I can confirm everything is working perfectly now. The total repair came to 1000 Euro for replacing the affected control unit which was found to be defective during the diagnostic scan. The fix resolved all the erratic speedometer behavior and the odometer has been tracking normally since then. No transmission issues or malfunction codes have appeared in the months following the repair. The ABS and traction control systems are also performing as they should. While the cost might seem steep, having the ECM communicating properly with all sensors is crucial for safety and vehicle performance. Based on the symptoms you described, your quote is probably in the right range since these control units require specialized diagnostic equipment and expertise to properly calibrate. The peace of mind from having it properly repaired by qualified technicians was worth the investment in my case. Just make sure they perform a complete system diagnostic to confirm the fix resolved all related issues.

Let me share my recent experience getting this fixed. After your helpful insights, I took my Q4 to a certified shop last week. The diagnostic confirmed exactly what you described, a faulty speed sensor and corroded wiring harness affecting the ECM signals. The total repair cost came to 950 Euro, which included replacing the sensor, wiring harness, and full system calibration. The speedometer now shows accurate readings and the ABS warning light has stayed off. My odometer is tracking normally and the traction control feels solid again, even in wet conditions. The shop explained that the transmission ECM needed proper calibration after the new sensor installation to ensure all systems communicated correctly. While the cost was significant, having the complete diagnostic and proper repair done has restored my confidence in the vehicle's safety systems. The peace of mind was worth the investment, especially considering the potential risks of driving with malfunctioning ABS and traction control. Thanks again for helping me understand what I was dealing with.