Phil, i'm currently putting my money on there being a permanently running timer, with a duration of about 20hours. At the end of a regen the pressure is measured and if it is low/normal the timer resets to 20 hours. but if the pressure immediately after a regen has completed then another regen is scheduled for a shorter period, by preloading the timer with a suitable value.
In yoiur case this means that when a regen has completed the pressure is checked, measured to be too high and the 20 hour timer is preloaded with, say, 70%, so that it counts up from 70% to 100%, instead of 0% to 100% for a 20 hour interval.
Timbo had a clogging value of 107% which I think just means that the 7% over 100 were as a result of not driving at a fast speed for a while. The timer keeps counting. Maybe it is just an 8-bit number and it counts all the way to 255 ?
Of course I'm guessing. Some more data would be nice to have.
For the kit. I like that the AlfaOBD software package makes it easy to graph data. I think Fiat ECU Scan also does that in a slightly different way, but i've yet to use it for that.
I'm sure other people have reasons for picking one over the other but they have both been able to do everything I wanted do so far.
The hardware interface is an ELM327. Mine was supposed to be fully CAN compliant, but like so many people who bought cheap ones off eBay I found that it wasn't working well over CAN. There is a very well documented fix, involving soldering 2 or 3 resistors to the pcb in the interface, which is what I did. The MultiECUScan (as for FES) info page linked to below actually has a list of interfaces which need to have a resistor removed.
I think by shopping around you can get FES or AlfaOBD with an interface for less than £70.
FES is now MultiECUScan and it appears there is a free version which lets yoiu do a load of stuff for personal use without paying Multiecuscan - Diagnostics software for Italian cars (Powered by FiatECUScan)
I know it's a bit of an area that most people don't want to get into, But I think it represented good value to buy this kit and have it, just in case. You can buy simple diagnostic code readers at Halfrauds for maybe £20 or £30 which lets yoiu recover fault codes and then you can start Googling what they mean, but for a few pounds more you get a lot of other features, such as being able to reset the oil service interval, realign the CAN bus if you change the audio unit, and so on.
The nice thing about both software packages is that they give you warnings before you start a procedure to say what the effect will be and if it is reversible or not. I've never heard of anyone screwing their car up badly from a bit of finger trouble, but I'm not saying it's impossible