So check the coolant level when the car is cold first thing every day before you drive it.
Any sign of the coolant level dropping, go straight back to the selling dealer without delay.
I would agree to check it once daily for the next 7 days or once daily for the next 7 times she starts it. After that, if no change, then no problem and perhaps only check once a week for "a while." If no change after that, then all is good.
BTW... did they remove the low coolant fluid switch on her model
? If my 2004 or 2006 dropped even the smallest amount below the min-fill mark, I would get the big "Check Coolant" level at startup with the bell and dings and a little error icon that stayed turned on the entire time the Touareg was running. If that system is still there, it really means that she should not have to check it more then perhaps once a week for the next month.
Also, while I agree that this needs to be checked out, this does not have to be the worst case situation. It could be, or it could not be.
With the amount of hysteria and the all is neigh here, I would recommend that she calls the service advisor at the first VW dealership. I would ask the service guy to please ask VW if there is any way other then the code they can check this system. If the mechanic could look it over, that would be great. At this point, $150 to the dealer might be better then the anxiety of "Is it going to blow up the next time I start it?"
We have a good start with watch the fluid levels. I would also recommend that she checks the oil level once a week for perhaps the next four weeks, just to make sure it is stable. Actually checking both of these fluids for the first month is good insurance on any used car you buy.
Speaking of that, as particular as these cars are with the "right oil" it might not be a bad idea to ask the first VW dealer if they would do an oil change and while you have it at the dealer, ask the dealer to have a mechanic look it over. Most of the dealers in my area love to do those free courtesy checks so they can tell you how many things you need to pay them to fix.
If the VW dealer can point at something on the EGR and say "Look there, see that crack or see that part is defective, then it will be really easy to get it fixed, even if the code has not reappeared.