I have taken this vehicle back 5 times for the DEF problem. They have changed the tank and the sensor but the problem continues. The warning comes on saying I have 9XX miles left before required refill of the DEF tank. 10 miles down the road it says I have 11XX miles left. Next time I crank up it says I have 3XX miles left. 10 miles down the road it says I have 5XX miles left. 10 more miles and it says 4XX, 10 more miles it says 8XX miles, then it says My speed will be limited the next time I crank up. The next time I crank up it says I have 4XX miles left before refill. This goes on for a month or so and then without warning my truck is limited to 50MPH. I get constant engine light warnings and OnStar confirms DEF issues. I take it in, and within a month after, it starts over again.

initially the vehicle was recalled and they added something to the DEF system. That was at under 10,000Mi. I told them that after that it seemed to use a lot more fluid and fuel mileage was lower too. No Solution... Then while on a long trip the message came on that I had 300 mi left on DEF fluid. Fine I didn't have near that far to go. However, 10 miles down the road the message says I am out of fluid and it will shut down to 55 on next startup. Since we were in the middle of nowhere I had to wait til I got home to put more fluid in. The message did go off. I toke it to the dealer who couldn't figure out why it did it. No gmc information on that kind of problem at that time. Of course they didn't put it on the rack and look... that was at about 20,000 mi. Now at 53,000 mi the system is going back and forth between DEF impurities to check engine light. now when in the shop and after warranty is off the DEF injector and 2 sensors need replacing. Cost 1500. Of course the rep states they will cover some. ( humm,.. some admission of an existing engineerijng problem?) Of course, the parts are not available. They will call when they are in. In the meantime I have a vehicle I can't use because it is threatening to shut down to 55 and then 4 mph. Great when I am off work for 5 days and have a ton of work to do. Not to mention that today is a big winter storm and I was unable to drive my wife to work in the blizzard. Good thing her Pontiac G6 is dependable and good in snow despite not having 4 wheel drive. Oh yeh, a great little car that they don't make anymore. Bye the way, Mazda has developed a disel engine that has low enough emissions that it dosn't need DEF system. Better mielage too. WAKE UP GM. No reason your Heavy Duty Trucks can't be dependable and get good mielage too.

The diesel exhaust fluid system on the 2011 duramax's are trouble. Everyone I talked to that owns one has had some sort of trouble. We were traveling south pulling our 5th wheel trailer, when it indicated that it was low on DEF. It had been filled 1800 kms. earlier, but we pulled over to fill the tank. When pouring in the fluid, it only took about a cup when it ran out the top. Thinking the filler neck had airlocked, we started out again only to have it say it was empty. When we pulled over to try and fill it again, it was still full. When we drove again, our speed was limited to 89 kmh. We drove for a couple of hours because we could not locate anyone to tow the truck and trailer. When we got it into the dealership, they had very little knowledge of the DEF system. When I called my dealership back home, they did not know much either. They told us the tank was full and they had to take the tank off, empty it and reset the computer. When they phoned GM they would get put on hold and GM would not return their calls. Finally they decided the tank and sensors needed to be replaced only to find out there weren't any in stock anywhere!! We assume they finally pulled one off of the production line. When all was said and done, we were stranded for 6 days!!! Why would GM sell a vehicle without informing their technicians or have parts readily available. Made for nice a holiday!