I can't remember if this (possible ways to damage the line) was discussed in your other topic about your crushed line but is this line and surrounding heating coil protected enough from driving over saplings (young trees) and other brush that scrapes against and has the potential to "grab" the undercarrage?Dealer thought that it might have still been getting some fluid, just not enough. Or the line continued to degrade. I have no idea what the ramifications are for that on the limp mode. It also could have had ice in it as I was driving through cold conditions and the heating coil around the line was broken when the line was crushed. There appeared to be some drop off in power when the light was on, but nothing like the zero boost that I had a week later.
I haven't seen where this line is located to have an answer for myself.
This has me a little worried since I didn't get an FX4 with factory skid plates (assuming the FX4 skidplates even protect this line). I couldn't get the 18 inch wheels with the FX4 package so I settled with only the 4x4 package.
The DEF line better not be crushed when my truck arrives (probably with the MY2012 trucks...lol).
(Edit; I just realized this isn't even on topic with your original boost issue...sorry).