What might cause my 2015 Mitsubishi Outlander Sport check engine light to come on?

The most common cause for a check engine light to come on in a 2015 Mitsubishi Outlander is a loose gas cap. If it's loose or damaged in some way, fumes will escape and trigger the light. Usually, tightening or replacing the cap will fix this problem. The next most common cause is a faulty oxygen sensor. This part monitors unburnt oxygen in the exhauSTSystem. The engine will still run, but if left unaddressed, this can cause damage to the spark plugs and catalytic converter. Speaking of spark plugs, if one plug, plug wire, or ignition coil is bad, this will trigger the light as well. If You want to save a bit of money, You can handle replacing these Yourself. It's a fairly straightforward task. The check engine light can also signify an issue with the catalytic converter, mass airflow sensor, vacuum leak, exhaust gas recirculation valve, or aftermarket alarm.