Does DEF go in a separate tank?
DEF is simply water and urea, with a 32. This solution of synthetic urea and deionized water binds with and helps neutralize harmful emissions in diesel exhaust. Also known as blue def, DEF is placed in a separate tank in a diesel engine, identified by its blue cap. If DEF enters the fuel system and spread throughout the engine it will ruin the diesel engine eventually. The fuel system lines are not compatible with DEF and slowly corrode and over time.A DEF tank stores fluid that cuts diesel emissions; keeping it full ensures proper engine performance.Can I run water instead of DEF? No, you absolutely cannot run water instead of DEF fluid in a modern diesel vehicle.All told, diesel exhaust fluid is just as important to your vehicle as fuel, coolant, oil and all the other fluids you regularly check and replace. Your machine will not function without DEF, and you can face serious consequences from letting the DEF tank run dry.