What Dashboard Warnings Really Mean

Like many other car features, dashboards have become much more advanced over the past few years. Little icons no longer light up only when there is a problem -- they can also indicate that the car is doing its job or is simply in need of some preventive maintenance, experts say. The variety of purposes for these dashboard lights can vary from vehicle to vehicle, which is why Alex Nunez, automotive senior editor for ConsumerSearch.com, says car owners "need to read their manual and familiarize themselves with the lights before they go on."

Fortunately for those who lost their owner's manuals moments after driving their new car off the lot or who bought a used vehicle that came with an empty glove box, we've put together a handy guide to the most common dashboard lights you may encounter. Read on to find out which, in particular, should warn you to pull over and call a tow truck -- and which serve a decidedly different function.Check engine lightWhat it monitors:The check engine light, which typically looks like a little engine, usually indicates there is a problem with the engine's management system or emissions control system. It doesn't indicate your car is overheating (more on this later).Should you pull over? If the car is emitting smoke or a funny odor, or making strange sounds, then yes, you should pull over to the side of the road and call a tow truck. If it's not, you might want to check your gas cap. "One of the most frequent reasons for the check engine light is that a car's gas cap wasn't tightened enough," says Phil Reed, senior consumer advice editor for Edmunds.com. He suggests tightening the cap and waiting a little while to see if the light goes away. If not, you'll have to take the car to a mechanic to have the problem diagnosed, as the light is what Nunez calls a "catch-all" that can mean a number of different things.

Temperature gaugeWhat it monitors:This light, which looks like a little thermometer, is the one responsible for monitoring your engine's temperature.Should you pull over? If it's red, you need to pull over and call a tow truck right away because, unfortunately, your engine is overheating. If it's blue, there's no need to be overly concerned, especially if it's not in a constant state of illumination. In that instance, "this is a courtesy light," Reed explains. "It's telling you not to rev the engine too much. You want to make sure the engine is warmed up and the oil is fully circulating before you do that."

Maintenance requiredWhat it monitors: This light, which either looks like a wrench or an abbreviation of its name, has become more common during the past few years as manufacturers have sought to reduce the number of reasons for the "check engine" light to go on. This indicator isn't letting owners know there's a problem with the car, but rather signifies the car is in need of preventive maintenance services, such as an oil change, filter change or tire rotation, which is triggered by the miles traveled rather than the specific performance of the vehicle."As you approach scheduled maintenance, the light will go on and stay on for about 30 seconds to let you know," Reed explains. Once your car is overdue for service, the light will stay on until the procedure it's calling for is performed by a dealer or mechanic and the light resets.Should you pull over? No, but you should schedule an appointment with the dealer or a local mechanic so that whatever preventive maintenance your car is due for gets completed.Traction and stability control icon What it monitors: This indicator light, which typically looks like tire tread marks or a car tipping over on a curving road, is tied to your vehicle's traction and stability system, which affects how the car handles and helps drivers avoid losing control on icy roads or during accidents.Should you pull over? If the light comes on and stays on, it's letting you know there is, in fact, something wrong with the system and you could be driving around without that added layer of protection that helps you regain control when swerving to avoid something or in snowy conditions. If the light flashes on momentarily, there's no need to call up a mechanic. "It will flash to signify that it's helping you drive the car," Nunez says. "It's actually a happy thing for you to see."Front passenger seat airbagWhat it monitors: "In older cars, both airbags would go off whether or not there was someone sitting in the passenger seat," says Brandy Schaffels, senior editor for TrueCar.com. She explains that resetting the airbags was rather expensive so, looking to avoid deploying passenger side airbags unnecessarily, manufacturers programmed newer vehicles to activate the airbag only if weight sensors indicated someone was sitting in that seat. As such, this light comes on to let the driver know that the airbag will not be activated.Should you pull over? Not if there isn't anyone in your passenger seat. If there is, you need to get the car checked out before you let someone ride shotgun, as the light is telling you there is a larger problem with your airbag control system.

Brake lightWhat it monitors: Newer cars tend to have more than one light that monitors its brake system (in which case, consult your manual, because this can be complicated). In older cars, Nunez points out, this is one of those indicators that "can signify two entirely different things": Something may be wrong with your brake system or you simply may have left the parking brake on.Should you pull over? Check to see if your parking brake is on. If it is, disengage it. If it isn't, pull over, as you can be low on or leaking brake fluid or have other problems that could lead the brakes to fail on you.

Tire pressure monitor systemWhat it monitors: In older and economy-class vehicles, this light typically looks like a little tire. Luxury cars, Nunez says, may "show the pressure in each tire individually." In either case, the tire pressure monitor system is, well, monitoring your tire pressure.Should you pull over? You might not need to have your car towed home, but you should visit a mechanic as soon as possible, especially since Reed points out that these lights are typically programmed to illuminate when tire pressure goes below 20%. "That's pretty low," he cautions."Your car won't handle as well if your tire pressure is low," explains Jack Nerad, executive editorial director and executive market analyst for the car valuation site Kelley Blue Book. "If it is very low, your tires can fail." Battery warning lightWhat it monitors: This light, which usually looks like a little car battery, is either letting you know the battery is low on charge or that there is a problem with the vehicle's electrical system.Should you pull over? Nunez explains that this light effectively means "you're on borrowed time" so, depending on where you are, pull over and call AAA if you expect to be far from a service station the next time you stop. Schaffels explains that this light typically indicates a problem that will make the car impossible to turn back on once it is turned off."Generally, even if your battery is weak, it's powered by secondary devices," she says. As such, you can choose to just cross your fingers and make a beeline to the nearest mechanic.Oil pressure gaugeWhat it monitors: This light, which typically looks like a dripping oil can, lets you know your car is low on oil. It may also indicate problems with the oil circulation system.Should you pull over? Yes, because, as Nerad points out, driving around with an insufficient amount of oil can wreck your engine, and having that replaced is certainly not as cheap as an oil change would be.Windshield wiper fluid gaugeWhat it monitors: This light typically indicates the fluid in your windshield wiper reservoir has run out.Should you pull over? No, the light is just telling you to add wiper fluid. According to Nerad, other fluid replacement icons that have become popular in luxury vehicles involve headlight washer fluid and exhaust cleaner fluid. These lights don't require immediate attention, though you will need to have the fluid replaced at some point.Follow TheStreet.com on Twitter and become a fan on Facebook. >To order reprints of this article, click here: Reprints