Check Engine light went on in mid-June 2018 with just over 77,000 miles on this 4 year old SUV. Several OBD code readers suggested 'reluctant tank temperature sensor failure or something like that. So, I elected to poke around online for information and there's plenty of issues with this technology. Ultimately I took it to the Dealer and their famed STARR machine! Sure enough........DEF tank heater element wasn't functioning.

Actually on the day I took it in, the truck was indeed blowing white smoke and the smell was more like ammonia so I knew there was definitely a big problem. Here's the real rules about Emissions warranty. 8/80 Fed is only for a few select components........not the entire thing. Hence the DEF tank is actually only covered for the basic 3/36. In my case, these particular parts were actually extended to 7/70 by MB after several heated complaints about them. Since my vehicle was over that 70,000 mile limit, you guessed it, not covered. I did however receive an $800 credit from MB USA to go towards the repair.

Everyone has there opinions, which seem to differ slightly as to the true culprit.......I think it's a combination of them all actually. In my case, this is a 2nd owner (first was a 2 year, 52,000 mile lease......Yikes! Imagine the additional mileage payment) and is native to California......the Anti-diesel State!

I found some blog from Stephens Automotive which I'm actually quite confused about. It's an old retired Mercedes only tech that seems to have extensive research on these Bluetec engines and basically claims that there is major design flaws. Anyway, most MB certified techs that I've spoken with have different opinions of these things. Between all the info on the web.....and face-to-face dealerships.....I'm actually in a neutral position on this vehicle.