There was a time when you had to learn what your car was telling you the hard way – by rolling up your sleeves and pouring through the engine piece by piece to find the problem. Now, with the advanced computer controls found on the majority of cars, our cars can actually tell us what’s going on with a simple diagnostic.

Unfortunately, the computers in our cars sometimes collect far more information than we know what to do with. And quite frankly, the car manufacturers don’t really want the consumer to do that much. So they’ve wired all of the information that’s gathering into one outlet – the check engine light.

But what does that really mean? The check engine light isn’t actually to be taken literally. You, as the driver, can look at the engine all day and you won’t see a thing wrong. What these lights are really saying is, “Take this car to the mechanics so that they can check the engine.” Of course, that would be a bit hard to fit on the dashboard.

Nowadays, when you go to a mechanic, he doesn’t look at the engine first – you tell him the check engine light is on and he gets out a device called a scan tool. The scan tool is basically a small computer that will talk to the computer in your car. The first thing it will do is show the mechanic a code that’s specific to both your car and what’s wrong.

With this information, the mechanic will know exactly what the computer says is wrong with your car. Some things will be major, some will be minor, and some – quite frankly – can be ignored. Yes, ignored. In fact, some people report having vehicles that have had the check engine light on for 175,000 miles or more without any issue.

Clearly, the check engine light being on tells you little – if anything – about what’s wrong with your car without the proper scanning equipment. You’ll need a mechanic with a scan tool to really tell you what’s going on. And in these cases, your mechanic’s judgment is another invaluable tool.

You see, the check engine light will come on for something as minor as a group of sensors going out to a leak in a non-vital system like the heating or air. Or it could be for something very serious – you have to go in to tell.

That’s where the judgment comes in – both yours and the mechanic’s. If he considers the check engine light trigger to be a minor problem, he may be able to reset the computer to ignore the signal and turn the check engine light off. Conversely, it may be a signal of a dangerous problem that needs to be fixed immediately. You won’t know until you take your car in.

However, you should never let the warning light take the place of actual physical warning signs. Strong vibrations coming up through the steering column usually mean a serious problem with a ball joint or a tie rod – in these cases, don’t wait for a warning light. Instead pull off to the side of the road, stop the car and have it towed to your mechanic. In addition, a battery light means a problem with the alternator, which means your car will be stopping shortly – whether you want it to or not. To be safe, pull off to the side of the road immediately.