DEF usage while towing?

[genestoy]

I am just throwing this out there to see what others think about this....I wonder if GM has programmed the DEF injection much higher when the computer knows there is a trailer connected? I really don't want to tow my trailer without the umbilical cord connected to find out, but was just wondering if maybe this is a possibility to keep the 3.0 within mandated emissions?

 

[StephenPT]

It functions based on two NOx sensors. Pre and post SCR - measured in PPM. When the engine is doing more work (towing) it produces more NOx, hence the DEF commanded is higher to meet the EPA NOx regulation.

 

[genestoy]

OK, that makes sense