2011 Duramax DEF mileage

[FARMER45]

I talked to a gmc dealer here in texas today he told me several of his customers are running just plain water instead of def
has anyone else heard this, he said a lot of the 18 wheelers are doing this?????

 

[Rickhansen]

I talked to a gmc dealer here in texas today he told me several of his customers are running just plain water instead of def
has anyone else heard this, he said a lot of the 18 wheelers are doing this?????

The owners manual indicates that this is not possible. DEF is a mixture of urea and deionized water and there is a DEF Tank sensor to measure the "quality" of the contents. I assume it has a precise conductivity by standards and any significant variation causes an error code. I would worry about it putting the truck into "limp mode" where the speed is limited to 5 mph. Either the info in the owners manual is blatantly wrong, or your dealer is.

 

[ricatic]

I drive the Ford 6.7 that uses DEF. The Federal Mandate for that type of emissions control is very specific on the parameters for monitoring the exhaust content down stream from the DEF injector. Use of any fluid other than DEF will result in non-compliance with NOX levels and the sensors would turn on a CEL...I call BS on the Texas dealer...

GM did have a temporary federal exemption issued on all of their 2011 DuraMax's because of DEF issues last winter. They reflashed problem trucks with a program that bypassed the entire system. Owners who had that procedure done had to sign an affidavit stating they understood that not returning to have the system reactivated when notified of a fix would lose their warranty. This program may be the catalyst for some GM owners that received recall letters.

Regards