We have a 2013 GMC 3500 dually with the 6.6 turbodiesel Duramax. Only 15k miles on it, so it's basically brand new. It gave us the dreaded "Poor quality DEF" message, and is now threatening to limit the truck to 55 mph.

I have googled the hell out of this, found an expired recall, discovered that there is no way to do this with a code reader unless you have the approved GMC code reader, and have otherwise exhausted my skills in trying to figure out how to fix this short of paying the GMC dealer a fortune.

If any of you know the sacrifice-a-goat-by-the-dark-of-the-moon cheat code for this one, please speak up.

DEF has a shelf life of one year, if you have already drained and refilled the tank , the dealer will have to reset it.

The DEF is fresh. Oil change just a couple of months ago, and they did the DEF at the time.

quote:

Originally posted by ArtieS:

The DEF is fresh. Oil change just a couple of months ago, and they did the DEF at the time.

Dealer service department maybe did not re-set the thingy at the time of the change. If that's the case, they should do it for you at no charge.

You can get a DEF (fluid) tester for around $30.00 at a parts store. I would check the condition of the fluid before anything else. It uses the exhaust sensors to monitor fluid condition, it had to set that code from poor fluid at some point or an exhaust sensor has failed.

I would not put that much faith in the dealership to have actually changed the DEF. Whether by mistake or due to negligence, dealers are known to charge for things they don't do.

Do recalls expire? If it's from the NHTSA and the recall has not been performed, it shouldn't expire. Are you sure it wasn't a TSB, technical service bulletin? Even then, it wouldn't expire for symptoms explained in the bulletin.

Are you certain the warranty has expired? During those years, a 10 year warranty on the emissions system was included.

I am told that this one expired. Wasn't a formal recall, was a GM service reimbursement bulletin. 10 years. We are sitting at ll years. Hoping since the truck is damned near new, we can get this done.

10-11 year old truck with 15k miles, it has definitely sat with DEF in it unless you drained it periodically. Crystallization

Do you know when the truck was put into service? That date is when the warranty starts. If you have a decent relationship with the dealer, they may be willing to work with you. Not all dealerships are bad.

Definitely will have crystalized over time of not being used. Can the system be flushed or must it be replaced? I'm asking because I don't know.

Heavy duty diesels started using an actual DEF quality sensor with EPA 13, model year 2015 I believe.
Prior to that the intake, outlet NOX sensors and DEF level sensor determined DEF quality.

To figure what's going on with DEF quality with no other faults, EGR, Nox etc. and no exhaust leaks.
1: Check DEF with refractometer or such.
2: Check that DEF pump is coming up to pressure, around 135 psi with no leaks.
3: Remove the DEF doser, check for a DEF deposit, can be as big as a baseball, usually caused by a leaking doser or poor duty cycle.
DEF Crystals melt around 800°, big rocks will take a while.
4: Pressure test with doser removed, check for leaks.
5: Flow test and check spray pattern.
6: Assemble and perform a regen while monitoring parameters making sure the NoX values are changing and not stuck in range.
If all that checks out, replacing the SCR is next.

Not sure about light duty but on heavy duty engines this isn't a fault that sets right away, can't just do a regen and say good to go when the MIL light stays off.
It could take a couple days of driving depending on the duty cycle for the ECM to gather enough data to verify.
A real PITA to troubleshoot sometimes and loading up the double barreled parts gun like you're running drills can get expensive fast.

quote:

Poor quality DEF"

From what I read on the innerweb, at the Duramax forum if you are not getting codes for the NOX sensors that you can

a) drive it 20 to 30 miles and it should clear as the sensors finally get cleaned out and get the clean exhaust signal provided the NOX sensors are good, or

b) go to the dealer and have them reset the ECM

https://www.duramaxforum.com/t...ality-reset.1011050/

I have a 2013 6.6 Duramax and the DEF system is a PITA. I feel for you.