Small update - we've decided that, rather than immediately replacing another sensor or the harness/loom, we'd go for one final (conclusive) test:
They're swapping over the supposedly-faulty sensor from the exhaust cam side of bank 2, with the exhaust cam sensor of bank 1.
I'll then do my best over the next few days/weeks to get the car to fault. Then, it'll either show a fault in bank 1 (meaning it must be the sensor that was moved over) or in bank 2 (meaning it must be the harness/loom on bank 2).
Fingers' crossed for the former, as a sensor is a lot cheaper & easier than the harness/loom.
I'll update once I know which it is
Edit: It's also worth saying that it's definitely heat dependent. Hot days and warm starts cause it to typically fault within about 45 minutes. Colder days, cold starts can mean up to 2 hours before it faults, or sometimes no fault at all. I agree that probably points more to the harness/loom than the sensor but, could still be a sensor issue.
To try and get it to fault then, I need to get out and get it really warm.
