The hermetically sealed reed sensors are ideal under harsh environmental conditions that typically exist in under-the-hood environments. Here the dirty, corrosive, expansive temperature range has no negative effect on the reed sensor’s operating characteristics. Reed sensors, unlike mechanical sensors offer remote sensing at distances greater than one inch. Of course, non-ferromagnetic metals and plastics offer no interference to their magnetic sensitivity. This allows the reed sensor to be placed in a benign environment out of harm’s way. Reed sensors do not require any power when they are in their off or un-energized state making them ideal for battery operated applications. This is not the case with solid state sensors that use power 100% of the time.