melblun - concur with all xkuz... says; I too have a 154BH. Another suggestion if I've not recommended it previously: inasmuch as your problem seems intermittent, check for spider web/infestation in or around your propane tubes to the furnace or in that area. Several of us have found that to be a problem. The web can be blown out with compressed air, should any of xkuz..'s advice be ineffective. Let us know.
'16 JAYCO 154BH SLX, Baja Ed
'13 Silverado 1500LT, 4WD, Ext. Cab, 5.3 ltr.,LNG BD
"Fair Winds and Following Seas"