Abstract: The invention involves a pressure fault device for indicating a threshold pressure or a threshold differential pressure. The present invention provides a cost effective way to determine where a pressure problem has occurred. The device includes a housing having at least one inlet aperture and an indicator aperture and having first and second bores in fluid communication respectively with one inlet aperture and the indicator aperture. The device further includes a magnetic piston which is biased in the first bore toward one inlet aperture and moveable a predetermined distance in another direction in the first bore in response to inlet threshold pressure. The device further includes a magnetic responder which is moveable toward the indicator aperture in the second bore in response to movement of the magnetic piston. The device further includes a latching plate in magnetic relationship to the magnetic responder when the piston moves the predetermined distance.