

However, drivers will still be treated to a dash full of warning lights and more frequent DPF regeneration cycles, so it’s best to not let the DEF run dry. This is allowed because the Cummins 6.7L engine tuning produces a low enough amount of NOx on its own, without the aid of SCR.


Currently, the only exception to this is the ’13-and-newer Ram HD trucks, which will continue to run and not de-rate power if the DEF tank should happen to run dry. If the vehicle is allowed to run out of fluid, one of two things will happen: either engine power will be cut and speed limited to essentially a “limp-mode,” or the vehicle will not start until the fluid is replenished. The warnings will get progressively more frequent, brighter, or louder as the level continues to decrease. Generally speaking, however, when the DEF tank level drops below 10 percent, a warning of some kind will be displayed on the dash, indicating it’s time to fill up. Some employ the use of a gauge, while some have a simple warning light. Vehicle manufacturers all handle this in slightly different ways. The EPA requires vehicle manufacturers have measures in place to ensure equipped vehicles cannot run without exhaust fluid. What can also leave you with a thumb out by the side of the road is running the DEF tank dry. DEF is not a fuel additive and never comes into contact with diesel. This system is called Selective Catalytic Reduction (SCR) and can be found on 2010 and later model year trucks and many diesel pickups and SUVs. This can potentially cause thousands of dollars in damage to the emissions system and leave you stranded. DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous NOx emissions into harmless nitrogen and water.
#SERVICE DEF SYSTEM SPEED LIMITED MANUAL#
The worst thing that can happen to an SCR system is being filled with contaminated or incorrect fluid. DEF Empty Refill DEF See Owners Manual Vehicle speed limited to a maximum of 5 MPH.
