Has anyone had to replace there coolant sensor before? or did you have to but a whole new coolant tank?

The coolant level sensor is in the overflow Tank.
On The LD9 2.4L -The coolant temp sensor is in the black plastic Coolant Bypass Pipe on the back of the engine that enters the head. (ie:drivers side where engine mounts to tranny below ignition module)

Note: sometimes the level sensors (in overflow tank) get stuck from coolant sludge causing the "Low Coolant" light on the instrument panel cluster to illuminate. An easy fix is to shake the sensor back up to "full" position with a good whack from a rubber mallet.
Don't Break the reservoir!

Hope this helps.

it helped thanks. Now I just have a slow leak somewhere.