My humidifier says er4--it is full and the light is on to refill the tank. I have had this for 5 years, so its not my first time using it. I reset the tank in to see if it was just setting wrong to try and get the light to go off, but it did not work. My manual does not have any error codes in it. Not sure if its life is just over, or if there is something I can do.