Diesel Exhaust Fluid on GM

[knotflying]

For those of us who have later model diesel trucks that use DEF. I have had issues with a warning notice of "POOR EXHAUST FLUID QUALITY" see owners manual. I will give you the short version: GM wants you to use only their DEF. DEF has a shelf life of 2 years so do not buy large quantities. If you get an exhaust fluid warning the recommendation is to top off the DEF tank and let the fluid do its thing. You will usually get this warning because of water introduced in the DEF. However it is a generic warning and can be due to other things. Once you get the warning you need to take care of your issue within 500 miles or the vehicle goes into a speed limiting mode of 55MPH after another 200 miles it reduces to 4 MPH. My problem turned out to be a bad NOX sensor, there is one upstream and one downstream of the particulate filter. The downstream one was shot and because of that the system went into a fault mode and sent the warning and kept pumping DEF as well as going into a regeneration mode on the particulate filter. Upshot after three visits to the dealer and the last one an 8 day layup with conversations back and forth to Detroit is I should be okay now. So should anyone have issues with this in the future ask them to also check the NOX sensors and DEF injector.
I have to say that the techs and Detroit worked diligently on this and were aware I was concerned about getting on the road trailering my boat. The thing that seems a bit unnerving is what happens when out west in the middle of nowhere with no dealer in sight? It could be a long ride through the Rockies at 4 MPH!

 

[R-Matey]

We appreciate your post concerning this matter. At the end of April we purchased a 2013 Silverado 2500 Diesel with 17 miles on it. We were not aware of this particular warning concerning bad quality exhaust fluid. We will make a note of your message.

However, we did have an issue one morning on the way to the Anacortes ferry where a message came up that our exhaust fluid was low and we only had so many miles left to drive before we'd be sent into outer space never to be seen again. We'd only had the truck three weeks. The exhaust fluid reservoir was nearly empty. We were not happy that our pickup was not fully serviced when we received it. Doesn't take but a minute to add the stuff.

Thanks again!

Ruth and Joe
R-MATEY

 

[Levitation]

Common dealer trick to save ten bucks is to only partly fill the DEF tank. Hopefully by then you will be in another state and not their problem.
I bought an 011 when they first came out. The mechanics who prepared the truck for delivery did not even know about DEF. When I got the warning I had done my home work on http://www.dieselplace.com so when the message popped up I knew what was going on. If you are a new owner go there and do some reading on the LML engines.
I had to go out in the shop and do a show and tell to teach them. They had to run down the street to the NAPA dealer and buy DEF as they had none. I was told later that when the dealer heard about it he ripped the service manager a new opening.
Mostly the DEF system is transparent. FIll the tank every 5k to 7k miles when the message pops up and that's it. I carry a jug with me for going to Florida.

 

[knotflying]

The tank holds 5.25 gallons. Rule of thumb is you use about 1 gallon per thousand miles.