The second lead, the KKL one would be far better, although I believe there is a little modification that needs to be done for it to pass on the battery voltage.
There might be pre-modded leads out there, and often you'll get a free CD with it that may or may not have some useful programs

INPA is a BMW thing, so if it doesn't come as a freebie, you'll need to look in various places and you'll probably find some download links.
This forum as a rule takes a step back from encouraging passing around software.
Back to the problem, I'd get the kit first and get that running and find out what the car was complaining about. It'll still hold it as a record, but it can be a lot of different things.
It's more common for the cause to be a disconnected pipe somewhere rather than an expensive sensor.