What Servicing the DEF System in Your RAM Heavy Duty Truck Really Means
What Does the 'Service DEF System' Message Mean on a Ram Truck?
When the Service DEF System light or notification illuminates on your Ram Heavy Duty truck dashboard, it means the powertrain control module has detected an operational fault in the Selective Catalytic Reduction (SCR) emissions hardware or fluid monitoring network. Unlike a simple low-fluid reminder, this warning signifies a mechanical or electronic failure