While waiting for the sensor to arrive, I suggest you update your controller (ProfiLux4 or Doser SA) to version 7.41 (ProfiLux4) or 1.53 (DoserSA).

The latest version of GHL Control Center 1.1.5.1, which includes this new firmware, says: “improved ION Director measurement algorithms: stronger sensor signals even with older sensors, increased accuracy and repeatability”.

https://www.aquariumcomputer.com/downloads/ghl-control-center-1-1-5-1a/#changelog

https://www.aquariumcomputer.com/knowledge-base/how-to-update-profilux-4-firmware/

https://www.aquariumcomputer.com/knowledge-base/how-to-update-standalone-doser-firmware/