Urea injection system wash cycle methods and systems are disclosed. An exemplary wash cycle method includes operating a urea injection system to provide urea solution to a first inlet of a blending chamber, provide pressurized gas to a second inlet of the blending chamber, and output a combined flow of pressurized gas and urea solution from the blending chamber. A pressure of the combined flow at a location downstream from the first inlet and the second inlet is monitored. A wash cycle is performed based upon the monitored pressure wherein the flow of pressurized gas is turned off and urea solution is provided to the blending chamber. An exemplary system includes a controller configured to control a urea injection system to perform a wash cycle in accordance with the exemplary method.