Error code 6 flashes. Have checked ground, good. Intake and exhaust pipes are good. It will light and run for 5 min. or so then the burner kicks off and blower motor clears out heat. It then starts flashing 6 code. Intake fan ist still running will run for 2 min. then shuts down till power is turned off and back on. Any help appreciated. Thanks Al

Open the front of the unit. Error codes are posted there. Then you can trouble shoot.