Mercedes E Klasse Diesel Heavy Steering Issue

I had similar symptoms on my E Klasse: increased effort, shaking. It turned out to be the steering sensor. Have you checked if the ESP light is on? Faulty coding of the sensor can cause those issues, which then messes with the traction control system. It might also be worth checking the steering column itself for any play.

Thanks, that's helpful. ESP light hasn't come on, but the symptoms are definitely there. When you say 'faulty coding', what exactly do you mean? Is that something that can happen spontaneously, or is it likely due to some prior work on the car? And how did you diagnose it?

By faulty coding, I mean the steering angle sensor's values might be off, or it might not be communicating correctly with the car's computer. It can happen spontaneously, although it's more likely if someone's been working on the car's electronics. A diagnostic tool can read the sensor's values and show if they're within the correct range. Honestly, I would get it to a workshop, it is more than just checking automotive sensors.

Thanks for the advice. Took it to a shop as you suggested. Turns out the steering angle sensor was indeed defective, coding was the issue. Cost me 195€, but at least it's fixed. They realigned it as well. Appreciate the help!