1. An imaging sensor disposed in a vehicle, comprising: an image acquisition unit for generating at least one image signal; and an evaluation unit configured to monitor the imaging sensor's operability based on the image signal; wherein the image acquisition unit includes a first image-producing sensor and a second image-producing sensor, and wherein the at least one image signal includes a first image signal provided by the first image-producing sensor and a second image signal provided by the second image-producing sensor, and wherein the operability is determined based on a comparison of the first image signal with the second image signal.