limp mode no engine light

See the funny thing is too it all.. is when we was calling around too the parts stores too understand exactly what an EGT sensor is and/or if anyone had one in stock, no one knew what was I talking about. Even calling the dealership the women that answered was clueless, and she had asked one of there mechanics, yet again clueless. I was almost wondering if theyre just giving me a run around at this point.. its been there over a week and they cant seem to figure out an O2 sensor? From my understanding the code was a diesel code (that is what the dealership said) making no sense too me at all considering its a gas engine.

Yeah only reason i know of the code is because I got the code and scanned it myself and googled it. But none of that is taken into consideration and they cant get the truck to send them a code? Because the engine light isnt on? From what i know it should have popped up soon as they plugged it in regardless if the light was on or not. I never cleared the code. I suppose one would assume that someone working behind the parts counter would actually kind of know what an EGT sensor would be.. as that was how it was worded, oppose too an o2 sensor.