A method for detecting and controlling the elemental sulfur deposition on pressure reducing gas fuel control valves in cases where the sulfur deposition results from a temperature drop during expansion across the control valve, such as that encountered in gas turbine engines. The control method and algorithm according to the invention uses measured parameters of gas flow rate, pressure and temperature, combined with known pressure reducing valve characteristics to first determine whether sulfur deposition has occurred, and thereafter to calculate a valve position control parameter used to control the gas temperature upstream of the control valve, thereby maintaining the sulfur in a vapor phase through the pressure reducing process and preventing subsequent sulfur deposition on the valve and downstream piping.