Def fuel light and check engine light on 2011 Kenworth

Did you run low on DEF fluid?

 

Is this a real question?
Do a parked regen then take it to the shop to get hooked to a computer to see whats wrong.

 

DEF generally doesn't have anything to do with DPF regen. There are separate indicators for DPF.

What engine? How much DEF did it take?

I'd look for obvious frayed wires and corroded electrical connectors in the DEF system.

 

Well the two times I've been in a derated truck they both were dpf needed cleaning.
In both cases they were freightliners and in both cases the def light by the fuel gauge came on with one of the amber check engine lights.

Both times I did a parked regen and that allowed me to get within 5 miles of the yard before derating again.

Point though, is that dash lights don't tell you anything really. The truck needs to be hooked to a computer to find why it's derated.

 

Most DEF tanks hold at least 15 gallons.

 

I would unplug the speed sensor and get back rolling. Also, the hose may have gotten pinched and the def tank thought it was empty and deranged. Same thing happened to a cascadia of ours two weeks ago.

 

Derated not deranged.