code p0705 is showing up on my 02 mercedes c240. what do i need to get?

A code P0705 indicates a transmission range selector switch problem, which would explain the poor performance and improper shifting from your transmission. I would have a good German car repair shop inspect your selector switch as it is most likely defective.

this is an obd2 trouble code table. it can help you understand the meaning of code. http://www.chinasinoy.com/service/how-to-understand-trouble-codes-37.html and for p0705 you may need to replace your transmission range switch also known as the park/neutral switch, they are known for going bad. It basically tells the PCM which gear the transmission is in. Depending on the application, they may cost up to $100 and you need to special order it through a mercedes benz dealer.