Triangulation photoelectric proximity sensor (1) having a first light emitter (2) for emitting transmitted light into a detection zone (3), a transmitting optical system (4), in particular a lens, being arranged upstream of the light emitter (2), a first light receiver (6) having an array of receiving elements (5) for receiving light from the detection zone (3), which is remitted by an object (7) to be detected, the receiving elements (5) generating respective received signals, a receiving optical system (8) arranged in the beam path between detection zone (3) and first light receiver (6) for generating a light spot from the remitted light on the first light receiver (6), wherein the position of the light spot in the triangulation direction on the first light receiver (6) results in dependence on the distance of the object (7), and a control and evaluation unit (9) for generating a detection signal from the received signals on the basis of the position of the light spot on the first light receiver (6), wherein a further second light transmitter (2) is provided as a reference light transmitter (12) for safety-oriented self-testing.