Mercedes GLS Stiff Steering and Sensor Concerns

I had similar issues with my old BMW, though it wasn't exactly the same. Steering felt heavy, and the stability control light kept flashing. In my case, it was a faulty steering angle sensor. If the sensor isn't reading correctly, it can definitely mess with the power steering and traction control systems. Have you had the wheel alignment checked recently? Incorrect alignment can sometimes cause issues with the steering sensor readings.

Thanks for the quick reply. Wheel alignment was checked maybe a year ago, but I haven't checked it since the problem started. When you say 'faulty steering angle sensor', was it a hardware issue, or did it require a software recalibration? Do automotive sensors tend to fail catastrophically, or do they degrade over time, causing gradually worsening symptoms?

In my case, it turned out to be a hardware failure of the steering sensor itself. I tried recalibrating it, but the error kept returning. These sensors can degrade over time, leading to inaccurate readings. Given your symptoms, especially the vibrating steering wheel, I'd suggest getting the steering sensor professionally diagnosed. It might be worth checking if your alignment is off again too. It's best to get it sorted at a workshop before it affects something else.

Thanks. Took it to the workshop; you were spot on. It was indeed a defective steering sensor. They replaced it, recalibrated the system, and the steering is back to normal. Also did a quick wheel alignment check as suggested. Total cost was 195€. Appreciate the help.