Since getting stuck with a "computer says no" DA-40 at Duxford, I carry a list of authorized dealers/repair centers/whatever for the plane I'm flying with me on foreign trips.
If you have something traditional like a PA-28 or C172, well, on most fields you can find an engineer who can fix things for you. But for FADEC-equipped engines such as the Thielert you need a laptop with special software and some sort of fancy connector in order to do the diagnosis. Not a lot of those around...
BTW. The signals for interception are also included in the general part of the Bottlang or Jeppessen flight guides. And I'm always updating my kneeboard with stickers containing precisely that sort of stuff. Also CAA landing/take-off distance factors, airspace VMC minima, wake turbulence hold times, marshalling signals, pax brief checklists, volmet frequencies, FIO and MET telephone numbers and so forth.