Check Engine Light Diagnosis: Causes, Risks & Free Scan Options

Last week I was driving to my fantasy football draft when my check engine light came on. “Great,” I thought. “Now what?”

It’s not a good idea to drive too far with your check engine light on because you don’t know what may be wrong.

Unfortunately, a check engine light doesn’t tell you anything specific, only that your vehicle’s computer recorded a malfunction in the engine or emissions systems. Until you get the problem diagnosed with a scan tool, you don’t know what that problem is.

 

What to Do When Your Check Engine Light Comes On

Get the problem diagnosed ASAP. You wouldn’t drive far if your oil light came on because your engine could seize. Likewise, you wouldn’t want to drive far after your check engine light came on because it could be something equally disastrous (or it could be relatively benign). The point is, you just don’t know, and that can be dangerous.

Where to Get Your Check Engine Light Diagnosed

You have a few options to get your check engine light diagnosed. You can take it to the dealer or an auto mechanic shop, to an auto parts store like AutoZone, or you can check it yourself with a scan tool.

Dealer or auto mechanic shop. We’ll start with this option because these are locations where you can get your vehicle repaired. However, be aware of any associated costs before you get your check engine light diagnosed. Some places may charge a diagnostic fee, which they may then waive if you get your vehicle repaired at their shop.

The advantage of getting your check engine light diagnosed at one of these locations is they can give you an in-depth diagnosis, repair estimate, and tell you potential problems if left unchecked. They may also be able to repair the problem that day or schedule a time if the problem is not critical.

Auto parts store. AutoZone is well known for doing free check engine light diagnostics. Just go into the store and ask someone behind the counter. The process only takes a couple of minutes and they will provide you with a print out listing the troubleshooting code and diagnosis, a definition and explanation of the potential problem, and probable causes. Keep in mind, this is all done from a computer and is not comprehensive! This is only meant to give you an idea of what the problem may be and will help you narrow down the troubleshooting process.

Also be aware that AutoZone is in the business of selling parts, not repairing cars, and while many of their staff are knowledgeable, they may not diagnose the problem correctly on the first try. Before buying parts on their recommendation, do some research into the problem and try to eliminate some possibilities.

Diagnose the check engine light yourself. Diagnosing a check engine light with a scan tool is easy to do. Just plug in the tool, turn on your car, and read the fault codes. The tools are inexpensive as well, starting at around $60, and going up to several hundred dollars. You can also reset the check engine light with a scan tool and see if the light comes on again (but do this at your own risk).

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Which is better – dealer/auto mechanic shop, parts store, or DIY?

There are pros and cons to each. The dealer and auto mechanic shop should have certified auto mechanics running the diagnostic, so you should have more confidence that they will diagnose the problem correctly. However, there may be an associated charge. With an auto parts store or DIY, you should get a good idea of what system caused the check engine light, but you won’t get a definitive diagnosis or necessarily know how to repair the malfunction.

If you are looking for the frugal way to handle this, I recommend dropping by AutoZone or another parts store that offers a free check engine light diagnostic and have them run a quick scan. It only takes about 5 minutes and should give you a good idea of whether or not you can drive your car until you can find a convenient time to repair the malfunction, or whether the problem could be serious and requires immediate attention.

If you have several cars or an older car, you may consider buying a scan tool. They don’t cost much money and it could help you deal with an unscrupulous mechanic who may try to pull one over on you by misrepresenting the problem with your car.

What happened with my car? Well, there was an Auto Zone on the way to my friend’s house, so I stopped by and asked them to take a look. The problem wasn’t one that needed to be repaired immediately, so I got the troubleshooting ticket from them and went on my way. I bought a new car just under 3 years ago, and since it is under 36 months old and has fewer than 36,000 miles, the warranty should cover the repairs. So I will make a date with my local dealership when I buy new tires and let them take care of the repair.

Question for the readers. Does anyone know of any auto parts stores other than AutoZone that offer a free check engine light diagnostic? The only place I have ever gone is AutoZone (because they were the only auto parts store I knew did this and the locations were convenient). Thanks!

photo credit: angel_srt24.