DEF Sensors or Dealer Errors???

[Roger75201]

Don't have a Heartland but I got to the Forum from a Google search on DEF Fluid problems. So this post is kind of a shot in the dark but hope it may help someone avoid my problem. Have a 2011 Chevy 3500 tow vehicle and have had many/ most Def sensors replaced at same GMC dealership. Two weeks ago getting ready for a two week trip to northern Arkansas a "Exhaust Fluid Low" message appears. I was going to fill the DEF tank anyway and I put all of one 2.5 gallon and emptied half of another-partial . Thought DEF tank had to be close to being full. On the second leg of the trip-approx. 550 miles from home I get a "coolant fluid low add coolant fluid". I now believe this was the 900 mile DEF fluid low message instead. I pull over and add a small amount of coolant and assume that the coolant sensor was just being very sensitive and go on. On third leg of trip while in the Ozark Mountains on blind S curves with grade I get a second "coolant fluid low add coolant fluid" message. Before I could find any place to pull over the engine shut down. I'm in 5-7% grade. Never had a DEF fluid message. Never had a warning light. Never went to 55 mph. But I ran out of DEF fluid at 700 miles on the trip with starting with the DEF tank at least 75% or more full. We are sitting on this blind curve two lane road and thankfully we had a cell signal. Called tow truck and state trooper. Limp to a pull off. Tow guy brings DEF fluid and resets codes. Shuts down again. So we find a Chevy dealership and they replaced the exhaust gas temp sensor and performed the regen to get the sensors set.

So we are home and I am searching on forums etc about Chevy DEF tank problems. Going to Dealer soon. But it seems to me that beyond the obvious of multiple DEF tank issues that GM has maybe my dealership never fixed my DEF sensor problems in the past. Coolant low message?? No DEF fluid low with mileage?? The only reason I bought the truck was to haul my 5th wheel.

Maybe this is a one-off but who knows.

 

[danemayer]

Hi Roger75201,

I used to have a 2011 GMC 3500 and had a number of DEF sensor problems.

I doubt very much that a "coolant fluid low" message would be about DEF fluid. The DEF messages in my experience all say DEF something or other. I don't know how it would confuse DEF with COOLANT.

Also, when you run out of DEF, you should get a DEF LOW warning at around 900 miles if I remember correctly. At 200 miles, you'll get more warnings. Eventually speed will be limited to 55 mph. The final step when you're out of DEF is to put the truck in LIMP mode, limited to 4 mph. I don't think running out of DEF, or any DEF error condition will shut you down completely.

I don't know if the exhaust gas temp sensor is related to the DEF system in any direct way. I'd guess it's not, but I could be wrong.

Behind the messages that show up on the screen, there are error codes logged. The dealer should be pretty clear on which error code is what. And if you know the error code, you can search more directly for cause of failure.

Btw, 2011 was GMC's first year using DEF. There were numerous problems with the firmware and with the sensors.

 

[lynndiwagoner]

I've got a 2011 and yes they had some problems with the DEF system. I bought mine used but after going to the dealer I was able to see what had been done by the original owner. The tank had been replaced early on and the NOX sensor had been replaced. Chevy recognized the NOX sensor problem and extended the warranty on it. I've since had one other sensor replaced. The message was "DEF poor quality" or something like that. At any rate, it might be worth while to get the APP "Torque Pro" for your smartphone so you can read the codes yourself and have a good idea of the problem. You might check with the dealer and find out if there is an extended warranty on your DEF system components. The LML engine is great and powerful but the emission stuff is sure a pain.