An initialization module in a pulse oximeter accommodates a variety of different probes and a variety of operating parameters as well as providing for interrogation of various probe circuits for detection of probe faults. Probe fault detection for the red and infrared LED circuits of the probe is implemented using an adaptive algorithm that is dependent on the drive settings or signals applied to the LED circuits. A configurable circuit is used to provide multiple initialization values relating to a calibration circuit of the probe for improved fault detection. Additionally, potential faults with respect to the photodetector circuit of a probe are identified based on monitoring drawn by an output by the photodetector.
