Diesel-powered Mercedes vehicles like the Sprinter are marvels of modern technology. They manage to have all the power and performance of a diesel engine while avoiding most of the pollution that typically comes from that sort of fuel. This is because the Mercedes Sprinter and other vehicles like it make use of what is known as DEF (Diesel Exhaust Fluid).
This article will walk you through DEF, why the DEF heater may not be working, and what to do when this very important system fails.
Diesel Exhaust Fluid
As mentioned, DEF is short for diesel exhaust fluid. It’s a special fluid that diesel vehicles need in addition to the standard ones like oil, antifreeze, transmission fluid, brake fluid, and, of course, fuel.
Composed of a specific mixture of urea and water (32.5% urea and 67.5% water, to be precise), its job is to react with harmful nitrogen oxides in the vehicle’s exhaust. This reaction converts the dangerous chemicals into regular nitrogen and water before it is expelled into the environment.
Since normal diesel exhaust is a huge pollutant, this system cuts down on emissions and generally helps the world stay a little greener.
The DEF itself is stored in an external tank with its own heater that is supposed to keep it from freezing during the colder months. What’s more important, most diesel vehicles have been required by law to use DEF to reduce emissions for nearly ten years. Because of this, if for whatever reason your DEF heater isn’t working as it should, you should not ignore it.
The DEF Heater
DEF is stored in an external tank and injected into the exhaust pipe to react with the nitrogen oxides right before the selective catalytic converter. Because it’s stored externally, however, that means that it is susceptible to the elements.
The freezing point of DEF is 12 degrees Fahrenheit (-11 degrees Celsius), and if the DEF is frozen, it cannot be injected into the exhaust. To keep this from happening, DEF tanks include a special heater whose job it is to keep the fluid warm enough to stay liquid. However, like all mechanical parts, this heater can eventually burn out.
Of course, if it’s a warmer part of the year, or you live in an area where the temperature never gets below 12 degrees Fahrenheit, this is not as much of an issue. In the winter time, though, the DEF may be at risk of freezing. Not only would this lower engine performance, it would also allow dangerous chemicals to be sent into the air. In many cases, your vehicle may go into limp mode or refuse to start at all if the DEF is not being properly injected.
In most cases, your vehicle will let you know before this becomes a major issue by turning on a warning light, but it’s always best to check for yourself from time to time, in the event that the sensor is not working properly.
Diesel Pickup Pros Will Repair Your DEF Issues
If you notice that you are having issues with your DEF heater in your Mercedes Sprinter, do not ignore the problem. Instead, bring it in to a certified diesel mechanic as soon as possible.
If you live in Indiana near Floyds Knobs, Georgetown, Jeffersonville, or New Albany, or in Louisville, Kentucky, Diesel Pickup Pros is happy to serve you.
We service the most popular brands of diesel pickup trucks, including the Mercedes Sprinter, Chevrolet Duramax, Dodge Cummins, and Ford Powerstroke. All of our mechanics are ASE certified, Chrysler, Ford, and GM certified, and factory trained, so you can trust that we will be able to help you with any problem. We keep our shop stocked with the latest tools and equipment so that we can ensure high-quality service for each and every visit, while remaining a faster and more cost-effective option than a dealership.
If you’d like to learn more or you need your diesel pickup truck serviced, we invite you to give us a call or stop by our shop today. Our friendly staff and expert mechanics would be happy to assist you. Call us today.
* Mercedes-Benz Sprinter image credit goes to: DarthArt.