Just about every day, we get asked if the “check-engine” light and ABS (anti-lock brake system) lights in a vehicle are really important. We have many customers who come in and are not overly concerned about those lights.

The “check engine” light tells so much, it just amazes me. Where else can you have something as complex as a vehicle warn you that something is malfunctioning or about to break down?

Recently we had a customer who came in for other repairs and said not to worry about the check-engine light, that he knew he needed an oxygen sensor but didn't think it was important. I spent the time to point out many concerns that I had about this.

First, the check-engine light comes on when something is malfunctioning or about to break down. It could be one of some 200 different problems, which will not be specifically located until a scanner is hooked up to the vehicle. If more than one problem is present, the light doesn’t light brighter or blink to let you know. It just comes on and stays on. Ignoring it can lead to a breakdown or a more expensive repair later. In the least, the car will run less efficiently and pollute more than it should.

In any vehicle, the oxygen sensor plays a critical role in achieving top fuel mileage with fewer emissions. It works by comparing the oxygen of the outside air with the oxygen in the exhaust. With this information, the control unit of the car can adjust the air/fuel mixture to the optimum ratio. A worn oxygen sensor not only decreases fuel mileage, it can ruin a catalytic converter by allowing too many hydrocarbons from unburned fuel to reach it. A bad sensor also can affect the drivability of the vehicle, causing it to run poorly.

By ignoring a check-engine light, you also risk becoming insensitive to other warning signs from your vehicle. My advice is to get it checked and repaired, keeping your vehicle dependable and running well.

As for the ABS light, its job is to tell you something is malfunctioning with the anti-lock part of your brakes. Not having ABS working in an emergency situation is dangerous. ABS will not allow your wheels to lock up, reducing your stopping distance and allowing your steering to work during hard braking. Remember, if the front wheel is locked up, your steering wheel has very little effect on the direction of your car. ABS is a wonderful piece of safety equipment that does save lives.

Finally, I want to touch on how far a car can be driven with the check-engine light illuminated. If it comes on, should you get your car towed or can you continue to drive it?

That’s a great question that I will not be able to answer with precision because there are too many factors to consider. With some problems that trigger the light, it would do no further harm to drive the car hundreds of miles. Others mean the car should not be driven more than two miles. The biggest thing to consider when making this decision is how badly the vehicle is running. If it is running very poorly, have it towed.

One of the worst possible results of continuing to drive a poorly running vehicle is causing excess hydrocarbons from unburned fuel to flood the catalytic converter. When this happens, the converter can overheat and melt down. We have had many customers who ruined their “cat” by continuing to drive poor-running cars, creating expensive repair bills.

If you can’t tell that the engine is running badly, however, the probability of damaging it by driving a few miles decreases immensely.

-George Rode