I was boosting along nicely when all of sudden "pssst", and the boost gauge goes to zero.

I found the vacuum line to FPR, ECU, Boost had blown off just at the moisture trap. So I thought it was time to redo all those lines with some new silicon hose but ... Then I noticed that the other vacuum line that comes off the intake manifold going to heater valves & diff lock was missing the line to the diff lock !

I searched everywhere and could not find it. Surely a mere 2Bar boost couldn't have vapourized it ...

The Diff Lock button seems to work ok, at least the light comes on. I didn't try any donuts to test if it was really locked. I'm perplexed !

Anyone got any pointers or photo's of where the diff lock line enters the engine bay and/or connects to the vacuum line ?

Therefore it will not directly affect the pressure on the vac line that feeds the ECU.

However, indirectly a disconnection on this vac line is still a leak which allows dirt/dust to get in, as well as boost to get out. When there's a boost leak it effectively takes more work on the compressor to produce the same overall manifold pressure - which can lead to excessively high spindle speeds, "instaplode" or bearing failure.