Precise and accurate engine internal combustion pressure measurements are typically built upon extremely low level piezoelectric sensor signals acquired in the laboratory. In turn, these minute signals must be conditioned accurately by electronic charge amplifiers then processed for meaningful analysis. Laboratory standard operating procedures often overlook the importance of timely and rigorous calibration of the equipment using sufficient environmental controls. In some facilities, years have been allowed between metrology-quality calibrations, introducing the potential for significant out-of-tolerance conditions and non-compliance to accredited measurement standards. Accurate and timely calibration supports the validity of using combustion data in engine design decisions, as well as avoiding development program timing delays, when additional unplanned testing becomes required.