M# 58GS050-EB

Owner call me to take a look at his furnace. He said he have been turning the power switch off and on to reset the system when the furnace wont recycle. I took a look at it on start up and electronic igniter will spark and lit the pilot but the igniter will not shut off until 20 minutes later. Polit will stay on for about 1-2 minute before the burner are lit. So my question is " is the ignition moduel faulty? or is there a flame sensor and is it faulty?