What Does The Check Engine Light Mean?

That little light can mean a lot of things. How do you know if it's a serious problem or just a small issue?
By Zach Bowman
One day, this might happen to you, you glance down at your vehicle's dashboard only to see the check engine light turned on. You burst into a cold sweat wondering just how badly your car's engine needs to be checked.

If your car doesn't sound like there is a monkey swinging a hammer under your hood and your vehicle is not billowing smoke, you're probably not in immediate danger (though you'll want to head to your mechanic to be sure). The check engine light, or malfunction indication light, as it's known to the auto elite, is designed to keep the driver informed of any number of sensor failures or engine irregularities. 

As automotive environmental standards became stricter throughout the 1980s, onboard engine monitoring became more and more complex. Today, a variety of sensors feed your vehicle's computer information on everything from ambient air temperature to the amount of oxygen in the car's exhaust gasses.

The vehicle's onboard computer, or engine control unit (ECU), then makes adjustments to ensure that the engine is running as efficiently, and cleanly, as possible in the given conditions. When one of those sensors fail, or gets a strange reading, you get the dreaded amber light of doom. So what do you do?

First, save the cold sweats for your yearly review with the boss. Things are probably fine, but you'll want to get it checked out regardless. Your technician will use a code reader - plugging it into your car's data port - that will display a numerical code that can be referenced to diagnose your car's problem. Most times the cross-referenced descriptions are less than helpful to a DIYer. You may get "fuel supply system" as the cause of your troubles. Unfortunately, the fuel supply system on most vehicles is made up of a slew of parts, and choosing to replace each and every one until you hit the trouble spot would be costly. Luckily, an experienced technician can decipher your car's woes.

Occasionally, there may be a simple solution to your check engine light dilemma, and these are things you can check yourself. Failing to tighten your gas cap all the way, not fully seating your engine oil dipstick or a loose oil fill cap can all cause the check engine light to flash. If you check all of the above and you're still stuck with a little extra amber on your dash, pay a visit to your mechanic.

If you haven't noticed any huge drop in performance when the light comes on, you can probably get away with putting off your check up for a short while. Don't take too long though, as the light may indicate the beginnings of a much more serious problem. Pull that piece of electrical tape off of the light, and get it taken care of.

Five Signs There Is No Serious Problem
1. Your car seems to be behaving normally
2. No strange noises
3. No smoke
4. No strange smell
5. You're getting the same gas mileage

Five Signs There Could Be A Serious Problem
1. A consistent rattle, knock or other unusual noise
2. Smoke
3. A severe loss of power
4. A serious decline in gas mileage
5. The vehicle does not start

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