Short version: is there a filter in the steering system?

Longer version:

I was chatting with the parts guy at the BMW dealer and I commented to him that my steering was kind of stiff but that the steering system was still working and that it had been this way for a long time...

Anyway, he told me that the same happened on his BMW 325 (same generation with M54 engine) and that it was caused by a clogged filter in the steering system. But he could not tell me where that was located.

Anyone know if we have such a thing?

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2001 BMW X5 3.0i, Automatic, Gasoline