Posted on 3/25/2023
Why Does My Dash Say Service Def System? This is a question we get a lot and many things can cause this and we will go over some of the reasons this message comes up on your dash. Another question we get is Why Does My Truck Have A DEF System? We will look at both questions and give you some answers of why Diesel Trucks have a DEF System and why the Service DEF System message comes up on the dash. We will look at Why Does My Truck Have A DEF System first. The main reason late model Diesel Trucks and Cars have a DEF System is to control the amount of Nitrogen Oxides (NOx) that the vehicle emits. The EPA has mandated that the OEM’s had to control the Emissions that the Diesel Engine emits. The DEF Fluid gets injected into the exhaust stream before the Selective Catalytic Reduction (SCR) unit. The Def Fluid goes through a mixing tube and enters the SCR unit, and the DEF Fluid reacts with the SCR and reduces the NOx and lowers the emissions coming out of the tailpipe. When the Servi ... read more