In Costa rica with a DL550. 300 hours. Getting poor DEF quality code even though is new fluid. Had tech come reset and tell me to change the def fluid. I did and message comes back after 30 minutes of use. Tech says they don’t have the equipment to check to see if a sensor is bad. Machine is inoperable at the moment . Any ideas what could be the issue?! Common problem ?!
just order the sensor and replace it. I had a 450B that had the same issue on a 25 model. First DEF issue I have had. I cant tell you how to do it, I have not had that issue with my dl550 but the engine is the same on the 450B as DL550.