I think you're right, it appears that this sensor is intergrated/bonded into the ISS system. I'm guessing this means I have to purchase a whole new ISS unit to get the external humidity working again ?
Am I right in thinking that the older Vantage Vue units had independent sensors that could be 'unplugged' and replaced ? If so, this feels like a step backwards on the newer units.
Overall it appears what I expected to be a cheap repair is now going to be costly..........disappointing overall.
Well, if it's an M revision then yes the harness is all-in-one. You can buy the complete harness and fit it yourself - it's reasonably easy to do, which is a bit cheaper than buying a complete ISS, though there's not a huge amount in it. (You do also need to identify whether the solar panel is separate (earlier M revisions) or included as part of the complete harness (later M units) - you need a different harness for each type.)
Yes, I can understand you thinking that it's a backwards step - Davis's argument is that the earlier pogo pin connectors on the separate components were a potential source of poor contacts and hence the all-in-one design is more reliable. I guess there's some truth in that, but I don't find it 100% persuasive, or, perhaps more to the point, don't necessarily agree that the trade-off is worthwhile.