A medical fluid injector (2) includes: an air detection system (122) for detecting air in the neck of the syringe; a hand-operated control lever (29) for controlling movement of the injection ram; magnetic conductors (94) for delivering magnetic fields from a power head face plate to an internal circuit board to permit detection of different face plates; a tilt sensor (158) detecting the tilt angle of the power head to control the speed of motion brought about by the hand-operated control lever and to control an invertible display (30); and monitor microcontrollers (192, 196, 198) for monitoring the behavior of central processing units (175, 192, 194) controlling the injector to detect and react to error conditions.
