I recently purchased a 2021 Newmar Dutchstar Motorhome, and took delivery recently. The Diesel Exhaust Fluid (DEF) sensor failed in less than 3,000 miles. As a newbie in the motorhome world, I was stunned and very disappointed that this failure occurred so quickly, and also with the ramifications of the failure. When DEF sensors fail the engine can go into derate state which can cause my coach to move at a maximum of 5 mph in less than a couple hundred miles, and then the engine SHUTS DOWN. I contacted Spartan...
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motors, the manufacturer of my chassis, and was told that this is a known problem with diesel engines, and that there is a worldwide problem with the DEF failures compounded by a worldwide shortage in functioning replacement parts. The DEF sensors regulation was passed by EPA in 2016, stating the DEF concentration be measured in the DEF tanks of vehicles. I believe that Shaw Development is currently at the sixth generation of the DEF sensor which are still failing regularly on brand new 2021 motorhomes. That is six attempts to make a part that continues to leave people on long trips stranded. As a female driving my coach, this is a major problem. First, because I cannot even drive my brand-new coach anywhere but also because the prospect of getting stranded on the side of the road, as a female, is too frightening to risk. And there is no prediction when I will get the part needed to repair the failure, or whether that part will be defective too.