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Tips for Avoiding 3 Common Problems with Diesel Exhaust Fluid (DEF)

Tips for Avoiding 3 Common Problems with Diesel Exhaust Fluid (DEF) - Truck To Trailer


Every day, the Truck to Trailer technical support team gets calls from customers covering any number of topics.A common engine-related call involves diesel exhaust fluid (DEF). Three issues we see over and over are:

    • Inadvertently putting DEF into the diesel tank
    • DEF contamination
    • Improper handling of DEF

Don’t confuse fills

DEF should never be mixed with diesel fuel, and it has its own filling port. But fuel and DEF tanks are close in proximity on some pieces of construction equipment, so it’s not surprising this mistake occurs.

Avoid contamination

DEF is extremely sensitive to contamination — for it to work properly, purity is critical. Contaminants around the fill cap can make their way into DEF and cause damage as well. If the area around the tank and cap isn’t cleaned before the cap is undone and fluid is added, it’s very easy for dirt or dust to fall in and get washed down into the tank. This can cause serious contamination-related issues — and cause unplanned downtime.

Other tips

  • Remember to change DEF filters regularly according to service intervals.
  • If the DEF tank is empty, the dashboard indicator light will illuminate and the engine will de-rate after a period of time.

It’s good practice to top off the DEF tank at the end of day. DEF tanks can build condensation, and that water can lead to contamination.

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