Mercedes SL Tire Pressure Warning and Steering Issue

That's definitely not just a simple low tire issue. I had a similar problem with my old Volvo, though the ABS light wasn't involved. The vibrating steering wheel and hard steering could indicate a power steering issue combined with the tire sensor problem. Have you considered a faulty tire sensor causing all of this? A defective tire sensor can cause pressure loss and trigger the warning. It could be a defective valve in tire.

So, you're thinking a single tire sensor could actually cause all these problems? Even the power steering feeling heavy? When you had your issue with the Volvo, did it also happen after you inflated tires?

It's hard to say definitively if one sensor is the root cause of everything, but it's possible. In my case, with the Volvo, the low tire warning and the stability control light were connected to a failing sensor. The heavy steering might be a separate issue or an effect of the ABS malfunction, which could be triggered by the incorrect data from the tire sensor. I would recommend going to a workshop, they could read out the data from the tire sensor.

Thanks for the advice! You were right, took it to the workshop and it was a defective valve in tire. They replaced the faulty tire sensor, and that seems to have cleared up the tire pressure warning and the ABS light. Steering is back to normal now. Repair cost me 280€. Appreciate the help!