Replace The Air Filter on a 2014 Ford Fiesta ST
Ford recommends you replace your engine air filter every 30,000 miles. It's really easy to do, and should only take a few minutes.
Note: The owner's manual states that the correct air filter is the Motorcraft FA-1914. However, at least one printing of the Fiesta ST supplement recommends the FL-1908, which is not correct. If you are still unsure, put your VIN into the Ford Parts Website and click through to Air and Fuel Delivery->Filters to find the right model number.
Locate the Mass Air Flow (MAF) sensor.
Pull up the red tab and unplug the MAF sensor.
Using a slotted (flathead) screwdriver, loosen the hose clamp and disconnect the hose from the airbox.
Using a Phillips head screwdriver, unscrew the four screws holding the airbox lid on.
The air filter can now be removed from the airbox and replaced.
Here's what the airbox looks like without the air filter.
Installation is the reverse of removal. Make sure you plug in the MAF sensor and push the red tab down to lock it into place.