Honeywell gas control 5 flashes

Customer has a water heater 10 year old ao smith. Filter and burner intake air area was cleaned about two months ago. Now the heater’s control is displaying a 5 flash sensor failure code. I assume that they are referring to the sensor in the control that measures the water temperature? Is the only solution to replace the control? I saw there was a way to reset it with a magnet, but given the fact that the control is 10 years old, I didn’t want to do a reset only for the problem to occur again in a couple days. Any responses would be much appreciated. Thanks to all