So i have OBD reader (BT one to a phone app) what now?

[glynh]

So got one eventually, mainly to see the DPF readings and check codes/etc.

I am not interested in any 'real time' readings when driving (RPM/etc), but just wondering if there are any interesting things that can be seen/done with it over just watching the DPF and how much it clears when a regen occurs. using the 'car scanner' app.

I have checked the codes and removed some old/archived errors (U0129 - didnt appear to be current by the wording and not had any warning lights/etc so not concerned)

So apart from the DPF readings are there any other ones that people like to view?

[Pidgeonpost]

I have the same setup and, like you, am interested in keeping a casual eye on the DPF. When we bought the car in February it would run a little lumpy for a few seconds on cold starting. The app picked up 2 failing glow plugs. I was intending to renew all 5 until I read somewhere that common rail diesels aren't as picky about cold starts as the older engines, so that one's on hold for a little while.
In the absence of a temperature gauge I was also interested to see if the thermost was doing its job, which it appears to be.

[Easington]

Auto transmission fluid temperature is useful (if applicable) to set the oil level correctly as it has to be between 50C and 55C IIRC.