Q - Why do you need one?
A -
read this especially the comment at the bottom in italic re D40s. It scared me!!
Q - There are reports around it's because the Chip-It chip raises EGT's to levels that could damage your engine. Is this correct?
A-
All chips (i.e. not just ChipIt) can raise EGTs. They can also reduce the temp too. If you run a hot tune then you are putting more diesel in. The greater combustion creates more power and more heat.
By adding the Chip It EGT gauge I have two levels of added safety built in. 1. I can readily view the temp at a glance and 2. It is wired into the Chip It chip and by setting an alarm the gauge will turn off the chip at a temperature that you can set.
Q - Do you recommend getting one and if so, did you install it yourself?
A - Yes is provides added insurance and Yes. I tapped a thread into the dump pipe and then braised the probe nut in place so that it could not undo. I then threaded the wire through the firewall and as you can see I cut a square hole into the auto selector surround. The gauge fits just perfectly in there (you'll see what I mean when you lift the surround out and look underneath).
I then needed power that was linked through the ignition so than when the car was turned off the gauge turned off. So I tapped the power wire up into the main loom that fed radio/CD etc. Getting to it is easy just remove the facia and radio etc and the loom is right there.
Q - Does a scangauge measure EGT's?
A- bugger if I know. However if you have an iPhone then DashCommand does or if you have a Windows phone or Android phone then Torque will measure it.
See this
post re OBD-II software for phones or ask Old.Tony as he is the IT man and can talk software better than I can.
If you want more install info let me know.
BH