What is the Check Engine Light?

You might be surprised, but one of the more common questions that I have heard asked by first time vehicle owners (and some not so first time car owners) is actually what is the check engine light? Believe it or not, it is true. Quite often I have tried to answer this in a slightly teasing manner, and you would definitely be surprised by the reaction I got. When I said that the check engine light was the "idiot light," a vast majority of people knew immediately what I was talking about, and no longer needed my answer to their question.

Now, I don't want to offend anyone my calling these lights the idiot light, but that is the best description of what they do that I know of. There is a technical answer to this question that goes something like this. These lights are a visual indicator of your vehicle's on-board computer of a malfunction that was sensed in one of the monitored systems. Basically, what this is means is that this is your car's way of saying "Hey, look at me! There's something wrong here!" And it's for this reason that I like to collectively call these lights the idiot lights, because (jokingly I assure you) you would have to be an idiot to miss them when they come on.

Now, while it is true that there are some differences between different models in vehicles, there is usually one similarity between them all. That similarity is in the idiot lights that they use for their cars. Below is a brief list of the different lights, and what they mean.

• Engine Service Light. This light can either be the actual words "Service Engine Soon," or a small picture of what looks like an engine. When this lights up it typically means that there is a problem somewhere in the engine itself, and that it needs to be looked at. Usually this is going to be something with the Electronic Control Module (ECM) which is designed to monitor your vehicles emissions. To be positive about what the problem is though, simply have it looked at by your mechanic.
• Thermometer. When something that looks like a thermometer lights up, it means that your vehicle is running too hot. Pull over, and let the vehicle cool down. Check you coolant levels to ensure that they are at the proper levels if they are simply have the vehicle looked at by a mechanic. If not then replace and check again.
• Battery. If a light comes on that looks like a battery, that means that you battery level is getting low, or that there is a drop in the amount of battery output. Check the connections on your battery, and if they are free of corrosion and properly seated then you should take your vehicle to a mechanic.
• Gas Pump. This light is only going to come on when you are running out of gas. To make it turn off, simply add more gas.
• Oil Can. When the oil can comes on that means that there is something wrong with your engine's oil. The simplest (and most common) reason for this to come on is that you are running low on oil, so simply refill to the proper level, and your light should go off.