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Diesel Exhaust Fluid Monitoring

Diesel Exhaust Fluid (DEF)

A non-additive solution consisting of a mixture of 32.5% urea and 67.5% de-ionized water. It is used to break down NOx emissions into less impacting nitrogen and water. The exhaust of diesel vehicles, it is often used in 2010 and later models.

About DEF System

A non-additive solution, due to emission standards adopted by the US Environmental Protection Agency in 2010, more and more trucks and engine manufacturers are using DEF in a system called Selective Catalytic Reduction (SCR). This technology enables medium- and large-sized vehicles to reduce NOx emissions into harmless nitrogen and water, thereby reducing their impact on the environment. DEF and SCR technology allows vehicles to meet newly adopted standards without compromising engine performance and fuel efficiency. At M&J Truck & Auto Repair, we can guide you on how and where to store it, fix applications on your vehicle, and we can even monitor your tank to ensure you never run out of fuel.

Tank monitoring DEF

We know you need to focus your attention on other things, so our specialists are prepared to ensure that your tanks have an adequate shelf life and that you never get left without what you need.

How often do you change a DEF filter?

  • Oil change and engine filter – 60,000 miles
  • Change in the fuel filter – 60,000 miles
  • Adjusting the valve harness – Adjust to 100,000 miles, 500,000 miles, and then every 500,000 miles thereafter
  • Change of diesel particulate filter – 500,000 to 550,000 miles
  • Change in pump filter DEF – Replace the filter every 3 years or 500,000 miles whichever occurs first


How do you know if your DEF fluid is bad?

The easiest way to detect a bad DEF is to examine it. The fluid is naturally bright, so if it looks cloudy or colored, it is likely to be contaminated or aged. Pollutants, including small particles, larger rocks, or dirt, will also be easy to see. If the DEF is not bright, do not try to use it.

Does DEF System have an expiration date?

DEF will degrade over time, depending on temperature and exposure to sunlight. Expectations for shelf life, as defined by ISO 22241-3, are the minimum expectations for shelf life when stored at constant temperatures. If stored between 10 and 90 degrees F, the shelf life will be easily one year.

If you have questions on DEF System contact M&J Truck & Auto Repair at 608-221-0526

Truck Repair Madison WI
DEF System
DEF System Madison WI