It requires a DEF Fluid Quality Test to clear.If anyone searches for this thread I would like to note that if you have a scan tool with a code clearing function that at some point the tool will no longer be able to reset the countdown to the reduced power mode. Or this was atleast the case with my 25$ tool. A professional tool may be completely different. In any case, relying on simply being able to clear the code before the car went 100 miles to the reduced power mode ended up sticking me with having to commute to work for 2 weeks with a 65mph top speed on the interstate.
Which can be manually done orrrr done by just driving it. But other than that there is no “Clear” button.