How can i fix my Bosch washer model wfmc6400uc?

How do you change a float switch for Bosch washer model wfmc6400uc? I believe the float switch is not working properly. I can still use the machine but before it goes into the rinse cycle, the machine alerts me to check water tap. I push the start button again and then the cycle continues.Is it the float swithc that i not working? Help, please.