Magnetic field sensor and related techniques can identify passing conditions, failing conditions, and marginal conditions of a sensed object. The magnetic field sensor and techniques can use one or more peak values of a proximity signal representative of proximity of the sensed object, can generate one or more difference values representative of difference between the peak values of the proximity signal and threshold values of a threshold signal proportional to the peak values, can categorize the one or more difference values into a plurality of potential categories, wherein at least one of the plurality of potential categories is representative of a respective passing self-test and wherein another at least one of the plurality of potential categories is representative of a respective marginally passing self-test, can assign category values to the plurality of potential categories, and can communicate at least one of the plurality of category values.