Seat Filter on Prem 2009 and up Maxima's
 

There are other write ups already on it but put the seat all the way up in the air and you can barely reach the filter from the back of the seat. A slight twist counterclockwise will allow it to drop down. Then you can wash it out....or replace it with a new one. I just washed and dried mine. I just did it because it was dirty. Good Luck and hope this helps