Some OBD ports have a plastic cover in front of them that says OBD. If your Fusion has this, pull the plastic cover down to access the port. Otherwise, just plug in your Onboard Diagnostics II (OBD-II) scanner.
Turn on the car without switching on the engine to power the scanner tool. Then, press Scan on the device so it begins running diagnostics. You’ll see a Diagnostic Trouble Code (DTC), appear on the screen. Read these codes to see what’s going on with your Fusion. Here’s what each character in the code means: