The Propex heaters were designed to be safe and reliable sources of heat for your vehicle. Being mounted in a non-stationary vehicle presents it's own challenges as the units are subject to vibration and exposure to all types of environments. Because of this, Propex designers err on the side of caution and create distinct operating parameters for the heating units. If the heater's electronic protection system senses that the unit is outside safe operating parameters it will show a fault code and shut down for inspection.
The five-flash code is triggered when the air flow sensor within the unit is not reading a nominal voltage, meaning it is out of specified parameters even before the heater is running and hot. This can be caused by something as simple as a blockage in both combustion pipes or as involved as a failed air flow sensor or main circuit board.
If you experience the five-flash code, first make sure both the intake and combustion pipes are 1M long and routed correctly. Next, remove your combustion pipes from the heater inlet and outlet and make sure they are clear. If the vehicle has been sitting or the heater not run in awhile, it may be that insects or rodents have taken up residence inside the combustion pipes or even in the combustion chamber itself. If the pipes are clear, try introducing compressed air (no higher than 30psi!) through the heater combustion inlet to see if something is dislodged.
CAUTION: THE AIR YOU PUT INTO THE COMBUSTION INLET WILL COME OUT OF THE COMBUSTION EXHAUST! BE SURE TO KEEP YOUR FACE AWAY!
If you're experiencing the five-flash code and the combustion pipes and chamber are clear, you have may have something more involved occurring with your heater. If the heater has been out of service for some time and the vehicle has been in a humid or moist environment, there may be corrosion on the air flow sensor itself. If your heater has been exposed to insects or rodents, it's possible that the main circuit board has been contaminated and fried. There is no self-repair recommended for the diagnosis and repair of the air flow sensor or main circuit board and your recourse is to contact us for repair. We have experienced and competent technicians at the ready to fix your heater as needed.
Check out the resetting fault codes procedure, as well.