The control system has detected flame sensing current out of sequence.
The burner has not shut down properly. Check gas valve for 100% closure. Check for flame candling after the heating cycle has ended through the Burner View Port, see page 11.
If burner flame is candling after the heating cycle has ended – replace gas valve assembly, see gas valve removal procedure page 15.
Call the technical support phone number shown on the water heater labeling for further assistance if the problem has not been corrected after performing the procedures outlined here.