Sensitivity-lowering detection function
WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
When the detecting ability of the radar is reduced by dirt, dust, or other contaminants, it signals the condition malfunction to the ACC unit until the problem goes away.