Propex HS-Series Heater Two Flash Fault Code

Propex heaters are designed to be a safe and reliable source of heat for your application. If mounted in a non-stationary vehicle, 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, a fault code will flash on the thermostat and the unit will shut down for inspection.

This article is for the Propex two flash fault code. If your thermostat indicator light is continually flashing two flashes between pauses, this article is for you.

The two-flash code is triggered by the heater's overheat protection sensor. Located in the heater air ducting, this sensor warns the heater's logic circuit when the temperature of the combustion chamber reaches a critical level. To minimize risk of damage to the heater or the installation location, the sensor shuts the heater down and throws a fault code.

This code often happens when the heated air going into the cabin of the vehicle is obstructed. Check for blockages in the ducting or move anything that may have fallen in front of the outlet vent. Let the heater cool down and reset the fault code by following this article:  Resetting Propex Fault Codes. Once the heater is cool, try running it again.

An overheat condition can also occur when the heat output ducting has an acute angle in its run. Though Propex sells 90-degree fittings, they should not be used within 15 inches of the heater outlet. All curves in the ducting run must be as shallow as possible. Similarly, if using a Tee-junction in your ducting, we highly recommend installing the long straight top of the tee inline with the heater output.  Using the 'center leg' of the tee inline with the outlet could cause overheating where the hot air flow hits the dead end of the tee.

If the two-flash code is not able to be cleared, you may have a failed heat sensor, which is not field-serviceable.  Please contact support@propexnorthamerica.com to initiate a repair.

NOTE: In HS2211 models, the two-flash code may be a result of water infiltration causing corrosion on the overheat sensor. The sensor will need to be replaced before the heater can be operated normally.