First thing, let’s clarify of which printer are you talking about. Is it an A1, a P1 or an X1?
Second, are you referring to the eddy current sensor? The one located above the hotend that detects whether the nozzle has made contact with the heatbed or not? Or are you referring to the Y-axis eddy current sensor?
Third, do you get a HMS_0300-1900-0002-0002 error? If you do, then the sensitivity of Y-axis eddy current sensor is too low.
Forth. on Bambu webshop do a search on "sensor ". You’ll most likely get a result like this:
https://eu.store.bambulab.com/en-be/search?q=sensor+&type=product&sort_by=relevance. Seek what you need and if found, order it. If not found, it might be because it comes directly integrated on, or part of a board circuitry.