A.O. Smith 110-310-510 – ERROR CODE 651 [510 (T-D2)] ABNORMAL FLOW ADJUSTMENT VALVE

1) Turn off power supply.
2) Check that all wire connections are secure and free of burns. The flow adjustment valve is located behind the computer board and attached to the cold water inlet.
3) Check for water leakage from the valve.
4) Do a visual inspection of the PCB. Check for connection/breakage of wires and/or burn marks on the board. PCB may need to be replaced.
5) The flow adjustment valve may need to be cleaned. To remove, follow the steps below:
a. Remove the four waterway clips on each side of the valves.
b. Slide the valve up off the inlet water connection.
c. Check both ends of the valve for sediment or debris. Use a brush or descaling solution to remove the sediment.
d. Re?install the valve and clips.
e. Test the heater.
6) The flow adjustment valve may need to be replaced if the valve cannot be cleaned.