Clean speed sensor on wheel

I have a 2011 Jeep Liberty Sport and the ABS and traction control lights come on in wet weather, and seem to go off once the weather is dried up.  The mechanics first instinct was to replace the sensor which involved buying a hub—$350 for labor and parts.  After reading some other posts I’m wondering if I need to clean the sensor and then apply dielectric grease to it and see if that solves the problem.   I also am wondering if I can clean and apply the grease without taking the wheel off—I don’t have the tools or expertise for that.