What might be the reason why the check engine light on my 2017 Ford Focus has turned on?

In a 2017 Ford Focus, several issues could trigger the check engine light to illuminate. The primary cause is a malfunctioning oxygen sensor, which monitors unburned oxygen levels in the exhaust and regulates the air-fuel mixture entering the engine. A defective air-fuel ratio sensor can also turn on the check engine light as it gauges the exhaust manifold's air-fuel ratio to control the mixture entering the engine. Additionally, a faulty mass air flow sensor, responsible for measuring incoming air and adjusting fuel delivery, could be a culprit. Moreover, a problematic ignition coil, which delivers electrical currents to the spark plugs, may result in engine misfires, rough idling, decreased power, or difficulty starting the engine. Other potential triggers for the check engine light in the Focus include various sensors scattered throughout the vehicle. If the computer detects abnormalities with any of these sensors, the light will illuminate.