The Espar Multi-Max F1000 heater controller serves the needs of the hydronic line of engine coolant heaters, and gives fleets complete control over their pre-heat coolant heaters. By introducing a desktop programmer and a Micro SD card slot, the Multi-Max gives fleets tamper-proof control of every aspect of every heaters’ operating parameters based on each vehicle’s individual work schedule. Users can program the heater to have as many as four distinct events per day, each with a different start and finish time, triggered on whatever day of the week that vehicle is in use. The controller includes a diagnostic indicator; a tri-colored LED with a simple flash code that notifies drivers when the heater needs either routine or unscheduled attention. Once in the shop, that same flashing code tells technicians the fault code causing the problem.