Most all of the plugs that are on the Slingshot have a sealing material that closes the connection to moisture and dirt. It would give extra protection if the proper grease was used. It is a special grease that conducts electricity.
Most conditions of fault that are temporary can be cleared by disconnecting the battery and reconnecting.
Let's all wait for chavey2 to report his finding of if the light comes back. We still have one more Wheel Speed Sensor on the rear.