2 check engine lights on and my DEF fuel light on but I just filled DEF tank

Have you ever used truck regen while parked ?

 

If the low DEF light is on that probably is turning on the check engine like. The computer probably is being told your low on DEF even with full DEF tank

 

Check the wiring harness around the def tank. I've had problem with them fraying and breaking off from the sensors.

 

Happened to me last week. Let the def level get down to 10%, then when I filled it up it lit up the warning lights like yours. Had to go to dealer to reset the codes too.

 

Rarely do people report back and say what the issue was and what they did to solve the problem. Did you find out what was wrong?

 

Seems if you let the def level get too low it sometimes triggers a warning code which doesn't clear itself when the tanks refilled, needs to be wiped by dealers laptop.

 

On a new Detroit most codes will clear themselves after three successful engine starts after the condition has been fixed.
The check engine lights should go out. But I find that the DEF yellow warning light still flashes. It acts as a tattle-tale if you completely run it out of DEF, I have the software to reset it myself.