What is code 859?

Sounds like you received just a bit of the information related to the fault code that was stored. In vehicles equipped OBD port (On Board Diagnostic, 1996 onward), codes are generally structured like this: Pxxxx i.e. P0420, or Cxxxx i.e. C1001, depending on which module generated the fault. If you have any other questions feel free to give us a call at (877) 913-1554 Dusty