2014 Cruze diesel with 100k. At 95k engine warning lite came on. Took to dealer and they said the heater element sensor in DEF container was bad. Replaced it for $400. Drove 3k more miles and lite came on again. Took it back and now they say the emission filter and system is bad and would run about $2,000. Being skeptical I decided to hold off and see if I could figure anything out. Warning light was out after being reset when at dealer 2nd time for diagnosis, so I drove about another 3000 miles with no problem. However, I noticed the DEF fluid level stayed at 25% all during that time. Engine light is now back on again. In talking to a diesel mechanic he said my problem is likely a plugged nozzle on the DEF injector since it was not using any DEF and it ran so long without lite coming on and no other issues. I would like to remove and clean, but need to know where to find it and best method of cleaning it. Shade tree mechanic, so hoping this is something I can do. Or would you recommend the BG treatment they have out now for diesels?