Nissan refers to them as a Generic Scan Tool (GST) which is an OBD2 scanner/reader which reads the computer module for the trouble codes when plugged in to the special adapter provided for it.......
They range in price from about $60+ and up into the hundreds of dollars.........Schuck's or AutoZone will read the codes for free, so let them know you're interested in the emissions reading......
Here's an inexpensive one I bought from Schucks (on sale), if you want to buy one, which shows the emissions:
OBD II Code Reader
