Nox sensor light on for 3 months but now gone out.

[pvn]

As title. In November 2022 the engine management light came on on my 2015 C Class 220d estate with 23000 miles on the clock. The local MB garage diagnosed the cause as a failed Nox sensor. None available as all on back order. The light stayed on until this week when it went off and has stayed off.

Any ideas as to why this might be? Should I replace the nox sensor when, eventually, they become available? All suggestions gratefully received.

Thanks.