What would cause my 2017 Ford Focus check engine light to come on?

There are many things that could go wrong in a 2017 Ford Focus that would cause the check engine light to come on. The number one reason is a bad oxygen sensor, which measures the amount of unburned oxygen in the exhaust and controls the air fuel mixture going into the engine. A faulty air fuELRatio sensor would cause the check engine light to come on too this part measures the air and fuel mixture in the exhaust manifold and helps to control the air and fuel mixture going into the engine. Another common reason is a bad mass air flow sensor, which measures how much air is coming into the engine and determines how much fuel to send. Finally, a faulty ignition coil, this part sends electrical current to the spark plugs and if it fails the engine could mIS Fire, rough idle or reduction in power and not being able to start the engine. There of course are other reasons that would cause the light to come on in the Focus, there is a plethora of sensors throughout the vehicle and if the computer detects an issue with any of them will cause the light to come on.