today my wife picked the car from the mechanic after an oil change - the mechanic told her that the oil level sending unit was leaking, needs replacement.

What is this part - what function does it perform? I have never had any oil leaks, nor does my car consume any oil, nor is there any problem with the oil pressure reading in the dash - 1.5 when hot at idle, goes up to 3 immediately on stepping on the gas even a little.

How serious is this? I want to educate myself before I call up the guy. I tried to look thru the search menu, couldn't find an answer to my questions.

Thanks a ton.

(85 190E 2.3, 123K miles)