I have a 2006 Htundai Ealantra and wish to know do i have to replace the whole trans or can the Solenoid be replaced




If the solenoid is bad, it's very easy to replace.  The solenoid is located on top of the transmission, on the drivers side of the engine bay.  It should be easy to see with a light and it is a relatively cheap part to replace; you can do it yourself in about an hour.

Which solenoid are you talking about? There are several solenoids on this transmission. They all can be replaced. Most of them can in fact be replaced without even taking out the transmission. Here is an example: