ABS Warning: Lateral Sensor Issues Plague Audi A3

As someone with some hands-on experience working on Audis, I dealt with a very similar issue on my 2013 Audi A4 2.0 TFSI. The symptoms you describe match exactly what I encountered, including the traction control being affected. After initial diagnostics, my mechanic found that the vehicle stability system was compromised due to a faulty control unit. The electronic stability program was showing errors because the control unit wasnt properly processing signals from the lateral sensors. The repair involved: 1. Complete diagnostic scan 2. Replacement of the ABS control unit 3. Recalibration of the steering angle sensors 4. Full system reset Total cost was around 1000 Euro, including parts and labor. The safety warning lights cleared immediately after repair and havent returned since. Before suggesting specific fixes, could you share: Current mileage, Any recent repairs or modifications, Whether the issue appeared suddenly or gradually, If you notice any changes in steering feel, The exact error codes from your diagnostic scan This information would help determine if your A3 is facing the same root cause as my A4 did.

Mileage is at 162956 KM and last service was 2 months ago. Connecting to your last point about error codes, I ran another diagnostic scan yesterday. The yaw rate sensor seems to be reporting inconsistent values when compared to the steering angle inputs. The vehicle stability system is definitely compromised, as the electronic control unit shows multiple faults related to sensor communication. Worth noting the steering feels normal, but the issue appeared suddenly after driving through heavy rain last week. No modifications or other repairs were done recently except routine oil change during the last service. The error codes point to a G85 sensor fault, though Im hesitant to just replace parts without being certain. Based on your experience, would you say its worth checking the wiring harness first before replacing the control unit?

Thanks for providing those additional details. Your symptoms are starting to sound different from what I experienced with my A4, especially given the sudden onset after rain exposure. The G85 fault combined with the timing suggests water intrusion might be affecting the sensor connections. Before jumping to a full control unit replacement like I needed, you should definitely check the wiring harness first since water damage is a real possibility here. On my A4, the electronic control unit failure showed consistent errors regardless of weather conditions. Your situation with the vehicle stability system showing intermittent sensor communication issues after rain exposure points more toward a connection problem. A diagnostic scan should reveal if the steering angle sensor and yaw rate values mismatch consistently or only under certain conditions. In my case, the faulty control unit produced constant errors. Before replacing any major components, consider: 1. Inspecting all relevant connectors for corrosion 2. Testing the wiring harness continuity 3. Checking for water ingress around the sensor mounting points 4. Verifying the traction control module connections This approach could save you significant money compared to the 1000 Euro I spent on the control unit replacement. Even if you end up needing parts, identifying potential water damage now could prevent future issues.

Based on your wiring harness suggestion, I definitely want to explore that route first since its much more cost effective. I pulled the codes again and noticed the steering angle sensor readings fluctuate more when the car first starts, especially on damp mornings. This seems to support your theory about water being the culprit. The yaw rate values do stabilize somewhat after the car warms up, which also points to a connection issue rather than a completely failed electronic control unit. Im going to take your advice and have my mechanic do a thorough inspection of the wiring harness and check all connections before we consider replacing any major components. Given that the vehicle stability system problems started right after that heavy rain, focusing on potential water damage makes a lot more sense than immediately replacing the whole control unit. I will start with checking for corrosion and testing the sensor connections. If we find any water-damaged components, I might also look into better sealing solutions to prevent future issues with the safety warning system.