NOx sensors exhibit an occasional problem; nonetheless, based on my experience, I assume their functioning is at the threshold of arbitrarily defined software settings. Having changed the NOx sensors on my C350 three times, I no longer pursue this issue. For the last five years, I have just dismissed the error code upon its annual occurrence and proceeded without any complications.
I believe that the recorded NOx levels sometimes above the designated threshold, triggering the code. The program has not been designed to address this unforeseen error, instead mistakenly resorting to a need for sensor replacement. I would want to ascertain the number of replacement sensors that have undergone appropriate testing rather than being discarded. Undoubtedly, Bosch or any other manufacturer would not advocate for an action that may result in significant financial losses from new sensor sales.