A printer includes a heating element and an active media shielding device configured to prevent print media from being overheated by the heating element. Each wireless sensor network comprises a plurality of Smart Sensors, each operable to measure one or more physical quantities. In preferred systems, even if a valve shaft locking bolt fastening the valve shaft is undesirably loosened during engine operation, the locking bolt is prevented from being completely removed from the retainer, thereby avoiding potential engine damage.