Hi Mike,
Sorry for delay in replying. As you have looked into the Carly and the software, you will have seen the prices for those items. In comparison to what the dealer is going to charge for the first hour it's a no-brainer!!
In all seriousness, I have found the Carly to be invaluable and has saved me quite a bit in time and money, as, if there is a fault, it will give the code from which you can identify the sensor where the problem is occurring.
For example, I changed all my brake pipes/hoses for the steel braided type (makes a heck of difference!) and although I bled the system, I was getting warning lights on the dash. I plugged in the adapter, fired up the ipad and it gave me the code 005E21. This turned out to be the sensor for the front brake line on the master cylinder, I did do a re-bleed of the system but all was fine, so, before paying out £25 for another sensor, I removed the sensor, cleaned it, replaced it and no warning lights. I've have been told that someone else had a similar problem and did exactly the same but the lights came back on after a week or so. If that should happen then it's okay, I will replace the sensor, but I know what the problem is and am able to solve it.
Can I just say, I have nothing to do with Carly and there are other adapters out there, but it is not just a one-off fault finder, it will be useful in times to come. There are a few sites on the internet that give the codes and their meanings and, of course, you can always ask on this Forum. I don't claim to know all there is to know about the Carly, there are many more folk out there that are far more savvy than I. But if I can offer help then it is my pleasure.
Hope this ramble will help
.
Colin.