Don't give up. It's possible. I just did it today. It was like a 23mm, but I didn't have 23mm (it might be more than 23mm) so I just used an adjustable wrench. I had the whole air box out, including the resonator piece, for other stuff I was working on. Then it was just a matter of wriggling my hand in there with the wrench, plus some PB Blaster to help. It is doable, just be patient.

Backstory to this was I am trying to learn INPA. Eventually I figured out I was getting an error code related to the oil pressure switch. So I ordered one. Coincidentally, while underneath my car one day doing something else, I noticed a random wiring harness not plugged into anything. Never thought anything of it, I just took a photo in case I could figure it out later on.

Sure enough, my code was because of the oil pressure sensor being unplugged. I didn't bother to plug it back in, as I had already bought the new one and who knows how much crud had been built up in the existing one. I used contact cleaner on the harness. Was able to get the old one out, not easy, but totally possible - no need to bring to the dealer for $600. Put the new one in and tightened it as best as I could.

I forgot to mention, yes, the diagram schematics are wrong. The thing is not pointed out the side, as the temperature sensor is, but it is pointed out the back of the housing. Makes it harder to get to. Probably why whoever worked on it last (dealer) didn't even bother to plug it in.