Faulty sensorsYour vehicle is loaded with sensors that measure everything from oxygen to coolant temperature, so it's not uncommon for at least one of these sensors to malfunction from time to time, in which case your check engine light may begin glowing. The oxygen sensor that measures how much unburned oxygen is in your car's exhaust system often operates in an environment exceeding 800 degrees, so it shouldn't be a surprise it'll eventually need to be replaced. A broken oxygen sensor can lead to the air-fuel mixture in your engine becoming inefficient, and you'll be burning more gas than you should be. Worse, a faulty oxygen sensor can also cause damage to the spark plugs and catalytic converter in your vehicle, causing even bigger headaches down the road.Likewise, the mass airflow sensor in your car can often be faulty, especially as it gets gunked up from use. This can lead to your engine jerking, dragging, stalling, or failing to start, among other problems. You can purchase specialized cleaners or save money by putting your mass airflow sensor in a Ziploc bag filled with rubbing alcohol to remove grime and dirt. Doing this twice a year or when you're changing your oil can prevent problems before they start or worsen and trip the check engine light.In addition to the oxygen sensor, coolant temperature sensor, and mass airflow sensor, your check engine light may indicate problems with your engine oil sensor, throttle position sensor, fuel pressure sensor, or coolant level sensor. The best way to determine a specific issue is by seeing what codes your OBD2 scanner brings up when plugged into your vehicle's computer.