Why dose the tras slip or not slect gear in a 1999 318i bmw and the yello light comes on in the dashboard

SOURCE: i have a automatic fiat punto-when i put the gears

Sounds like you need a new gear box or you can get your old one reconditioned at a gearbox specialist. i think your ploblem occourd because you may of had no gearbox oil inside the gearbox

SOURCE: Peugeot 205 1.2 Junior, Slipping Clutch

see if thete is any adjustment left in the clutch cable if not then you will require a new clutch

SOURCE: Transmission slipping in drive and transmission whining.

SOUND LIKE TRANSMISSION IS SLIPPING.CHECK THE TRANSMISSION FLUID MAKE SURE ITS NOT LOW.ALSO IF TRANSMISSION FLUID LOOKS DIRTY DARK AND SMELLS BAD REPLACE FLUID AND FILTER.IF FLUID IS GOOD YOU HAVE.TRANSMISSION OIL PUMP AND FORWARD CLUTCH PROBLEMS.

SOURCE: 2002 kia optima slipping into 3rd and 2nd gear while driving

UPDATE! ! ! Fixed this problem! YES ! ! ! The speed sensors was all that needed replacing. NOT ANY SOLENOIDS ! !. Two of them cost $160 and it solved the problem! Do not buy from the dealers. An after market version is available for $50 each. I was forced to buy dealers.

SOURCE: BMW 1988 325 Dashboard orange check light stays on while driving.

The orange light is probably the pads wear indicator showing that the pads are worn out and the cutting out probably you need your car serviced and tune.
Cheers