Don’t Panic When Your Check Engine Light Comes On

August 5, 2015

I’m not at all what you would call a car guy, but that’s exactly why I decided to write an article on this topic. As someone who knows little about cars, and has seen the check engine light come on in his cars more than a few times over the years, I’m starting to become something of an expert on this problem.

If you’re like me, or at least like the me that I used to be when I knew nothing about this, you probably panic anytime the check engine light comes on. While it’s almost inevitable that it will create an uneasy feeling – mostly because you don’t know exactly what it means – it’s too early in the process to panic. In most cases, it’ll be something less than a certified disaster.

Here are some steps you should follow if your check engine light comes on:

Keep Calm – It’s Most Likely Something Simple

To a person with no mechanical orientation at all, the check engine light coming on is unsettling to say the least. But it may help to know that in most cases, the reason that the light comes on is due to something that’s very simple, and highly fixable at a low price. It might even be something you can repair yourself.

Yellow Light OR Red Light/Flashing Yellow Light

In most cases when the check engine light comes on, it will be a constant yellow light. Less common are either a red light, or flashing yellow. There’s a world of difference between the two.

The constant yellow light is a true warning light. Its purpose is to alert you to the fact that your car is in need of repair, however it is not a critical situation. You can continue to drive the vehicle, at least for a short while, and at least long enough for you to figure out what’s wrong and what to do about it.

A red light or flashing yellow however mean something entirely different. If that is the warning signal you are getting, it’s an indication that whatever is wrong with the car is doing damage to the engine. That means it’s time to park the car, and have it towed to a  mechanic without delay.

Many times there is no choice. When the red light or flashing yellow light come son, the car often stalls out only minutes later. But if it doesn’t, you’re going to have to act quickly to prevent more costly repairs.

What we’ll discuss from this point forward is what to do in the more common scenario of the constant yellow check engine light.

Get a Diagnostic Done – For Free

When the check engine light comes on – again the constant yellow light – you need to have a computer diagnostic done on your car. The check engine light is tied into your car’s computer, and will provide codes that will indicate what the problem is. It will generally list several, with the most severe listed first, and the rest appearing in descending order of importance.

Sometimes the codes point to different problems, and it can seem as though your car is about to die forever. But in many cases, when you fix the primary problem, the rest of the codes go away. This is likely due to the fact that a malfunction in one component of your car’s engine will affect others. Although there are times when multiple codes do actually indicate multiple problems.

Getting the diagnostic done is a simple process, and you can generally have it done for free if you go to an auto parts store, such as AutoZone. Many people decide to take the car to the dealer when the check engine light comes on, but this is the most expensive route. A dealer will often charge you as much as $200 just to do the computer diagnostic, but make you think you’re getting a deal because they’ll waive the fee if you have the repair work done in their shop – at an even more exorbitant rate.

But considering that the check engine light generally indicates a low-end problem, you should start with a free diagnostic at an auto parts store. It will let you know what the problem is, and you can decide how to proceed from there.

Consult With Your Automobile Brain Trust

One of the things I’ve done over the years – and that I strongly recommend if you are not educated when it comes to cars – is to create an automobile brain trust. This is the group of two or more knowledgeable car people who you can consult when these problems arise. They can be friends, family members, trusted coworkers, and yes, even your mechanic. When it comes to car problems, it’s best to have multiple opinions. That prevents you from paying too much for major repairs, when the actual problem may be something much less significant.

The auto parts store can give a general idea as to what the codes in the computer diagnostic mean. Armed with those codes – and explanations as to what they mean – go to your automobile brain trust and start asking questions as to which way to proceed.

It’s Most Likely Something Simple and Inexpensive to Repair

In the vast majority of cases when the check engine light comes on, the source problem is something simple, and relatively easy and inexpensive to repair. In fact, according to CarMD, the five most common check engine repairs are:

  1. O2 sensor (part of the emissions system, monitoring and helping adjust the air-fuel mixture)
  2. Loose gas cap (which will cost you nothing to fix)
  3. Catalytic converter
  4. Mass air flow sensor (monitoring the amount of air mixed in the fuel injection system)
  5. Spark plug wires (this is also a very inexpensive fix, but sometimes the problem is the connecting wires, which are a little more expensive to replace)

Generally speaking, none of these repairs are worth losing much sleep over. You might even be able to fix one or two of them yourself, or have it done by one of your automobile brain trust friends, and your car will be back on the road in no time.

If it isn’t something simple – and that is a possibility even with the constant yellow light – get your car into the shop. The possibilities could be endless. But not until you’ve tried all the easy stuff first.

Have you ever panicked when the check engine light came on, only to find out later that the cause was no big deal? It’s actually quite common.


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Kevin Mercadante is professional personal finance blogger, and the owner of his own personal finance blog, He has backgrounds in both accounting and the mortgage industry. He lives in Atlanta with his wife and two teenage kids and can be followed on Twitter at @OutOfYourRut.

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One Response to Don’t Panic When Your Check Engine Light Comes On

  • Nega Alemayehu

    I have jeep grand Cherokee v8 limited mang.daye 1999 and my car maintenance is in good cpmdition but those. 2 dsus showed check engine yellow colore. then what is your advice. Thankyou.