W203 c240 sedan transmission problem
 

My brothers c240 had a problem today with the transmission. Prior to the problem the car was fine. Transmission started to slip and eventually would not engage Drive gear. Check engine light came on as well. P0715 & p0730 codes. Anyone with experience with these 2 codes? There is also a loud whinning noise when the accelerator is pressed coming from the general transmission area

Searching on Google and here on the site leads me to the Conductor plate being worn/no good but the loud whining noise inside the transmission makes me believe that there is another problem than the Conductor plate

Ditto, the P0 715 does indicate a conductor plate failure.
But trans noises are not related unless the filter is plugged from clutch material.

How about low fluid?

Paul