What Does the Check-Engine Light Mean?


That is a signal that the onboard diagnostics system (or OBD II) has detected a malfunction in the vehicle's emissions, ignition or fuel systems. It could be something as simple as a loose gas cap or something as severe as a faulty catalytic converter, so you shouldn't ignore it. All cars and light trucks have onboard diagnostics that are supposed to detect engine-related problems that affect the emissions control systems.

The check-engine light (typically a yellow or orange outline of an engine with the word "Check") should come on for a few seconds every time you start the engine with other warning lights. If it stays on, that means there is a problem.

If the check engine light is flashing, that usually indicates a misfire or other serious issue, and it should be dealt with quickly at an auto repair shop. Ignoring a flashing light increases the chances of additional problems, including damaging an expensive catalytic converter (which costs more than $1,000 to replace on some cars).

If it isn't flashing, before rushing to an auto repair shop you should first tighten the gas cap because a loose cap can trigger a warning. See if the light goes off after several engine starts over the next day or so. Replacing a worn gas cap that doesn't fully seal may also solve the problem.

If that doesn't do the trick, an auto technician will need to diagnose the problem by electronically tapping into an OBD II connector under the dashboard to read diagnostic codes that will help isolate what caused the light to go on, such as a bad spark plug or oxygen sensor.

Even if your vehicle seems to be performing well and your mileage isn't dropping, it's a bad idea to just ignore a check-engine light. Something is wrong, and it's likely to get worse. In addition, if you live in an area where vehicles have to pass periodic emissions tests, an activated check-engine light usually means your vehicle will automatically fail.

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Guess I shouldn't mention that you can determine the problem yourself with an OBDII scanner and a smartphone for less than $15-20....


What a useless feature. With today's technology you would think there is a place to display a useful description of the actual problem somewhere instead of creating a 'panic' or 'ignore' scenario.

me - "How long has the light been on?"
them - "ummmmm I don't know, it's running fine?"


I agree with DC. With so much electronics built into cars nowadays, why not display for the driver in some screen what is wrong?


So the dealer makes money and makes up an excuse to charge you. Talk to a trusted mechanic or a place that doesn't charge for a simple inspection.


they wont display codes and stuff on the dash ,because an error code in itself may not tell you where the problem is at ,no offense but if you cannt read obd codes your probably better off taking it to a mechanic


I'm a girl who knows nothing about checking engine codes until i researched it online. It's pretty easy and I was able to enter my code and look it up on line to see why my check engine light was on. I drive a pt cruiser and for me it was simply turn the car on (but not over) three times then read the codes that came out where the odometer is (where you usually see your mileage). Write down the numbers then google them.


I just bought a used car and it runs smooth, but the engine light came on and stayed on. I just checked the gas cap and it may have been loose. I will see tomorrow when I go for a short spin.

Great article! This covers check engine light issues in detail too: http://www.insureplan.net/check-engine-light


why does my fuses blow out when I turn the key?

Alphaeus N. Ogini

Please , i have a volkswagen touareg 2004 model , 6 cylinders . i have problem withmy , the problem are (1) the car jerks whenever i speedup apply brake , (2) the back tyres drags from time to time. pls help me find problem somi can fix it . i love my so much


I wish I have seen this earlier. I just spent 18.00 at currier motors. a engine programmer was 700.00 , with a few other thing. I only have 34,500 on a 2006 PT cruiser. I am a senior lady. And theres also more to this. I am going to look into this.


i spend 1,800 on a pcm reprogramer for a enging light.to bad i was so dumb. thers more to this then i could ever write

dorian gillens

Hi I have a saab 95 and it's shuts off soon as I start it and the engine light is on?What can it be and it has 180, 000 miles on?

Kate Maxwell

I'd say that don't trust the new technologies. YES, they are great. NO, they are not always right. No app, no electronics can replace an experienced mechanic. I've experienced the inability of these electronic and digital services and ability of repair and service centers. I stick to the basics now, regular checkups and maintenance at Service Plus (www.serviceplus416.com), a known service center at our place. It looks like my engine lights or other warning signals doesn't have any purpose of life :D

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