We’re all into saving money these days. But you simply can’t skimp on the quality of your DEF (diesel exhaust fluid) because the DEF level sensor will fail. Like a ticking time bomb, you’ll typically see a warning light on your dashboard accompanied by a countdown to engine shutdown.

We can’t emphasize enough the importance of trusting your DEF supplier. Here at RV Jensen, we are your one source for top quality bulk DEF fluid. Diluting or substituting another type of fluid simply doesn’t work.

There is no DEF alternative. Here’s why:

The DEF solution is specially formulated to clean up diesel engine exhaust. The composition is precisely 67.5% pure deionized water and 32.5% high-purity urea. DEF enters the exhaust stream once it passes through the DEF head. It is injected into diesel exhaust before it enters the Selective Catalytic Reduction System (SCR system). The SCR system reduces levels of NOx (nitrogen oxide), which are harmful to the environment and to our health. Once in the SCR, the exhaust becomes simple nitrogen and water and safely dispels into the atmosphere as a non-pollutant.

The DEF head monitors the quality of the engine’s diesel exhaust fluid. If the DEF is contaminated, the DEF head sends a warning signal to the engine and then your dashboard lights up. The vehicle will be forced to shut down or only allow you to drive at 5 miles per hour when running on imposter or contaminated DEF.

Is the problem your DEF fluid, or something else?

Sometimes, the fix is a reset to the DEF sensors. Other times, the DEF head requires replacement. With the global shortage of parts and chips, DEF heads can sell for thousands more than pre-pandemic prices, leading some to remove their entire DEF systems. Others resort to clearing DEF codes before the engine shuts down, risking ultimate engine failures by continuing to operate with a DEF head issue.

Any modifications to a vehicle’s emissions standards are illegal.

The DEF sensors and DEF head may not be the root cause of your issues. Problems could stem from substandard diesel exhaust fluid.

Look for these telltale signs of DEF issues:

  • Dirt or Metal contamination: Rust, tank scale, or dirt can be the result of improper DEF handling and storage.
  • Urea dilution: Too much water in the DEF reduces its effectiveness. Therefore, topping off DEF levels with water can negatively affect concentrations.
  • Crystallization: Topping off DEF levels with water can also lead to crystallization deposits in the injector nozzle or the exhaust. Crystallization can occur when too much DEF is added to the system, plugging DEF pumps and DEF lines.
  • Cold Weather: Temps at 12˚ F and below can cause DEF fluid to freeze or gel, rendering a halt to engine operation. Pouring in additives only exacerbates the problem by upsetting the concentration of urea and damaging the SCR system.
  • Contamination from Other Fluids: Diesel fuels, engine oils, and coolants should never be added to the DEF tank and will only wreak havoc on the SCR system, ultimately leading to engine shutdown.

How do you know if your DEF will work?

  1. Only purchase your bulk DEF from reputable distributors to ensure that the correct mix of high-purity urea to deionized water is exact. Here at RV Jensen, we only provide brands of DEF that carry the international standard of ISO22241 and are certified by the American Petroleum Institute (API): Yara’s Air1® DEF and Vulcan Companies’ TerraCAir Ultrapure DEF™ and Blue Sky DEF.

DEF is easy to handle—It’s nontoxic, nonflammable, non-hazardous, and nonpolluting. Its harmless composition poses no serious risk to humans or animals when handled properly. Store DEF in a cool and dry area that is well ventilated and out of direct sunlight. DEF is corrosive to brass, copper, and other materials, so it should only be stored in the DEF tank and packaging equipment earmarked for its storage. For optimum performance, make sure you use your DEF within 90 days of purchase.

  1. Check, maintain, and repair your DEF system. Bring your fleet to Advanced Emission, a branch of RV Jensen to clean the DEF nozzle and change your DEF filter. Your DEF service includes fluid testing:
  • Testing for Contamination—If the solution is cloudy or colored, your DEF may be contaminated or old. Besides visually inspecting your DEF, we also run an Insoluble Matter test for cleanliness.
  • Testing for Concentration of Urea—We test to ensure the target percentage is at 32.5%.
  • Testing for the Introduction of Other Fluids—We take a sample of DEF from your tank to determine that it is free from diesel fuel, antifreeze, engine oil, or hydraulic oil contamination.
  • Testing for Crystallization—We test for free-flowing DEF injectors and evidence of minerals in the fluid.

Could your DEF tank be contaminated by a DEF alternative or from the mishandling of the solution? Could you need new parts or need to replace your DEF head? Call our experts to find out. Contact the Advanced Emission team at (559) 240-6076 to schedule a service, and reach out to our DEF specialists at 800-366-8210 for bulk DEF delivery to your fleet and customers.