I'm about two days into having to get serious about OBD whatever. My Canter is 2005 and doesn't really have an OBD2 socket (it has one wire) which I believe I can remedy.
Enough excuses though. There are things called PIDs (Parameter Ids). There's the number they have inside the ECUs, and the label they have in the software. In Torque, like most other live data viewing programmes, there seems to be a way of defining "custom PIDs". Its a trial and error process. The numbers in the ECUs seem to be two digit hex. The labels in the software seem to be of form Pnnnn.
Its done that way because originally there was only one ECU, now there's an "ECU for everything" and the OBD connection communicates through CAN Bus to all of them.
Not easy to get right though. There are also calculations from raw data to display.
There's odds and sods about the ECU numbers in various places. There'll also be the effect of any translation MUT has done.
Wouldn't mind guessing there's a monster configuration file for Torque and other software that has the cross-references by vehicle.
P1335 is EGR related for some makes. Somehow need to look at the PID (or at least the equivalent translation for the error code) to the two digit number for the engine ECU - its in my engine service manual but Owen tells me its not in his.
Not much help sorry, I'm still trying to figure out why my ECU reported the engine running backwards.

Though in looking at this problem I've read that 45 means the two engine speed sensors are a bit out of phase, which sounds much better than engine running backwards.