A 2015 Nissan Altima’s
OBD II port (or diagnostic link connector/DLC) is located underneath the dashboard, to the top right of the pedals—more specifically, the port is just above the brake pedal. It’s pretty hard to miss as the black safety plug plugged into the socket is marked as “OBD II.” Once you’ve located the OBD II port, do the following:
Make sure your vehicle is off and in “Park.”
Remove the OBD II safety plug.
Turn your ignition on, but don’t start the engine (when using a generic OBD II scanner, check the instructions as to whether the vehicle needs to be in “ON” or “idle” mode).
Wait 5 seconds and connect the scanner’s connector cable to your vehicle’s DLC. The connector will only fit in the port one way, but it should be obvious how it plugs in.
Once connected, the OBD II scanner will automatically link with your Altima’s engine computer. Let the reader scan the computer—a process usually only takes 4 - 5 seconds—and wait until the LCD screen says “Done.”
Unplug the OBD II scanner and switch the ignition off.
Take the scanner to an AutoZone technician and give them your vehicle identification number. The technician will connect the scanner to a Z-net terminal to generate the report, explain the readings to you, and recommend possible solutions.
Should you ever use a personal OBD II scanner rather than one from AutoZone, the process will be slightly different—always check the instructions before using one to avoid damaging the device.