So I think I might be into something....
I was looking around and came across these units which have sensors (circled in red)
Then took mine out (this is the section leading to the driver side footwell vents) and realized mine doesn’t have this sensor (as expected) nor a grommet.
However, it does appear to have markings where it would be located IF it were to be equipped.
The harness and surroundings you see in this following picture appears to be identical to the on in the shop manual picture.
If someone has fitted the sensor without drilling anything, can you please share where you installed it (and please don’t refer me to the work shop page Tom posted in page 7 lol)
Drilling a hole is sounding so much easier lol