A self-adjusting luminaire whose primary operation is to provide ambient or focused lighting in a hazardous environment is configured to modify (e.g., continuously) the energization intensity levels of its on-board illumination sources based on magnitudes of difference between an amount of light in the environment of the luminaire (e.g., including both light produced by the luminaire and ambient light) as measured by on-board sensors and a setpoint amount of light corresponding to the luminaire. Further, the self-adjusting luminaire may detect that its on-board sensors are malfunctioning when the illumination sensors fail to sense a change in the amount of light in the environment of the luminaire after the luminaire has modified the energization intensity levels of its illumination sources. Upon detecting a sensor malfunction, the self-adjusting luminaire may generate an alarm, and/or may automatically modify the intensity of its illumination sources to mitigate effects of the detected malfunction.