i have a error cod P1836 on my 2001 ford expedidition A4wd .. i think it comes back to a speed sensor on the transfer case wher is this sensor located .. can i fix it myself? or need to take it to the dealer and how much do these sensors cost .. Thank u all for ur time

 

That code refers to the front sensor or it's circuit. It's mounted on the outside front of the transfer case, held in by one bolt. As to the price...there's a lot of online parts suppliers to look that up.