I have a 2001 BOSCH 4.6.
I am suspecting that the 4 pin temperature sensor located on top of engine that I recently replaced is faulty or calibrated incorrectly. My engine has Secondary Air Injection and the only temperature sensor I can find (Part number MEK100160) is for non Secondary Air Injection vehicles. My current sensor looks the exact same with 4 pins etc.
I can’t find a part number for the sensor associated with the SAI system engines.
Does anyone know if it will make a difference if I use this sensor instead of a sensor that’s for SAI engines?

I don't think it will make any difference as the SAI system has it's own sensor in the bottom of the radiator (or at least some do I understand). Neither LRCat or JLRs own site list a difference between SAI and non-SAI, they both list the same sensor you have. The sensor you have is actually two sensors in one body, one to feed the engine ECU (which is the one that the Nanocom will be taking the reading from) and one to feed the dashboard gauge.

It seems, from looking at my fleet, that early 99 and prior years do not have a sensor at the bottom of the radiator for SAI, but late 99 and up do have this sensor.
Yours being a 2001 will indeed have this one. I had an issue with a dirty connection at said sensor on one of mine. A quick clean took care of it.

Sensor that I was sent turned out to be faulty. Replaced with a used one from my donor P38 and all is right in the world…