Deco Super Combo 4400 E12 fan code issue.

The unit shuts off at about 3 minutes into the sensor drying cycle and set E12 fan code. However, I can set unit on time dry for 2 hours and fan and dryer operate as they should. I have checked wiring connections, drain filter, exhaust fan operation, and for any signs of Lint build up that I can. It's my thoughts the moisture sensor may be bad causing the the fan to shut down. However, I can't actually find the moisture sender to check it. I could be the main circuit board? Any ideas or solutions would be appreciated. Thanks