Have a 5+ year old Rinnai 556FAIII Rinnai Gas Direct Vent Wall Furnace. Recently having problems with an error/shut down of unit. About a month ago, the unit went into error mode. I fixed it by pulling the cord and restarting. Now, the unit goes into complete error and restarting will not fix the problem. The unit reads flame failure. Every time a call for heat initiates, the heater will go through its normal startup procedure. I can hear the sparker, see the flame ignite and the blower activate. After about 3 seconds, the flame cuts out and the blower continues runnning putting out cold air. Tried searching the boards with no luck. A service call in my neck of the woods runs $250.00 +. Any help greatly appreciated.....

Thanks