How to Fix Your Check Engine Light.





Introduction: How to Fix Your Check Engine Light.

About: Awesome Gear I've designed myself.

Fixing your car doesn't have to be expensive. Thanks to the age of information, anyone can be a "Google Mechanic". While this specific repair may not match your situation, it's the same process. So let's get rid of that annoying orange light.

A word of caution: if you have little or zero experience working on cars or using tools don't do this alone. Find someone who can work along side you to help prevent accidental injury or damage.

Step 1: ​Buy an OBD Reader.

Really, it's worth it. OBD stands for on board diagnostic. A reader will cost you about $60.00. You can buy one at auto parts stores or even Walmart. It may sound like a lot, but keep in mind, just pulling your car into a mechanic's shop will cost you a minimum of $75.00. That's just to look at it. At least this way you'll always have it and you can help your family and friends later.

Here's the basic principle of how OBD works. Your car has a computer which receives input from different automotive systems. When these systems send the wrong input (something is broken) the computer records the problem and turns the service light on. Plugging in the reader displays the code/s the computer recorded. These codes are generic diagnostic codes and not specific to a model (yes, there are exceptions).

We'll go over how exactly how to use a reader in a later step.

Step 2: Scan for Codes.

It helps if you've paid attention to your car's performance prior to this point. If your vehicle has an emissions problem you may not notice any change in performance. Or, on the other extreme, your car may not even start. Being aware of what symptoms your vehicle has will help you pinpoint the problem. In my case my SUV was having a hard time starting especially after filling the gas tank. This was intermittent for about a month.

Look under the lower edge of your drivers side dash board. You'll find a trapezoid shaped port for the reader. Plug in the reader while the engine and ignition are off. Once connected, turn the key on but leave the engine off (KOEO). Press the scan button and watch the the reader think. It will eventually display codes stored within the computer. Scroll though the codes and write them down. In my case the code is P0496.

Step 3: Search Your Code.

So you have a code, now what? The internet is filled with all kinds of forums and threads. Often the code your vehicle has is a common occurrence with your vehicle. You'll find people have fixed it and written about it. A great website is It will give you a good understanding of what your code/s mean. If your know a thing or two about cars then this will help. If you don't, don't worry. Yes, it helps to know how something works before you fix it but you can get by here.

Search the code along with your vehicle. So here's what I wrote in the search bar. "Buick rendezvous OBD P0496." You might also add your vehicle year but keep this in mind. Vehicle models change year to year but what's under the hood may stay the same for years. If your vehicle is a 2008 and and the post is for your model but 2005 the fix could be the same. I found a post which said it could be the purge valve based off of my symptoms and code.

Step 4: ​Locate the Part. Remove and Replace.

So now I suspect the purge valve but what is it? What's it look like? Where is it? All these questions have answers you can find by doing an internet search. I found this diagram showing the purge valve. I compared it under the hood and located the part.

Once you know what the part looks like you can order it with confidence. I bought mine at autozone and replaced it in 10 minutes. It was a matter of 1 bolt, 1 hose, 1 electrical connector, and $24.00.

Step 5: ​Erase the Code.

Now that the part is changed, plug the reader back in. Press and hold the erase button. When the screen changes press the button again to confirm. The code is gone now and your check engine light should be off. This is assuming you have no other codes.

Important: if you're fixing a problem to pass a smog check, drive your vehicle for a day before taking it for testing. The technician can tell if you recently (within 50 miles or so) deleted the code. He will collect his $24.95 and tell you to come back again. If your check engine light is on when you show up, it's also an automatic paid fail. So make sure it's off before inspection.



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    Please be positive and constructive.




    burtis I have a 93 Subaru loyale with a check engine lite on and can not find the geen connectors under dash to check codes? does 93 have them?

    I have a 1998 dodge grand caravan and the check egine light comes on it will run but i have to keep my foot on gas and my oil smiles like gas i need help please

    I love people that try to fix their own cars. After $$$ they bring it in to me to get it FIXED. :)

    11 replies

    so what do you to help your fellow man?????

    What I really love is when my friends bring their cars by after they've been to the shop and spent money to have a problem not fixed. Then it turns out to be a cracked vacuum line.

    All because the "professional" mechanic just plugged a scanner in and started firing the parts cannon, rather than actually diagonosing the issue.

    Thank you sir or ma'am. keldredge, you
    may very well be and likely are an honest mechanic inferring a well
    intentioned point in your comment. However, Tk42967 is
    making a valuable point as well.

    I've personally lost count of
    how many BS "fixes" I've payed for or been "prescribed". I once went in
    needing only a new drum and rotor (or w/e, you know what I mean) to be
    told I needed a new $800 axle (AND that I may as well throw in a trans
    rebuild for several grand because "I'll need it soon"). The car was
    "used" in the most extreme since of the term. I payed less than the
    price of the recommended "repairs" for it, by far. That's the most
    extreme example on the list, but it's a LONG list.

    If I (as the "layiest" of laymen) have any advice to add to that of the 2 former's smart advice it's this:

    you do find a trustworthy mechanic, treasure them like gold because they
    are quite literally MONEY IN THE BANK! Short of that though, try to go
    in with as much knowledge as possible (e.g. - an OBD), and the first
    whiff of BS - about face and double time it because as soon as they get
    their hand in your pocket it won't come out until you owe them those
    pants along with everything else you have, er HAD
    rather! Oh yeah, and your car will probably be 7 more different kinds of f'd up than when you walked in.

    P.S I realize I speak anecdotally here but I know I'm not the only one either. If 1,000,000 chicken littles show up squawking - seek shelter!


    Very well said and I agree whole heartedly.

    see my other posts !

    Cheers !

    Been there, seen that... Our Meriva had misfiring/stopping dead problems. Two "official" services and thousands of dollars later we found an "ex service" mechanic who diagnosed and fixed the problem within a couple of days. Since then we've taken the car to him. Good workmen deserve their wages.

    you "sound" like a nice guy

    Yep, a very "nice" kind of person who takes joy out of others problems.

    Thought you would take the pain out of the problem

    The truth hurts, but facts are facts. It was my job to fix them, and earn an income.

    I like smug people. It's all the more enjoyable when life reminds them that they aren't perfect and it wipes that smug smile off their face.

    I SEE you have been thru the ringer, as so many people have let me no the state you live in im in nc



    After 30+ years of being a mechanic mostly doing smogs and driveablity. Code scanner will only tell you what system is out of range. As time has gone on they have gotten more complicated. Most models have pattern failures meaning they often have the same problem. Due to part or system weakness or failure. If you think you know what the problem is and do the repair your self and the same code comes back it's time to stop wasting money and take it to some one trained too. A local school repair training shop my be a good idea.

    Two things:

    - Don't overcomplicate things. If your car/truck/interstellar space craft is fairly new or you have little reason to suspect it requires service, stop the car, remove and replace the gas cap making sure it's threaded in properly and sealed, then drive the car for 10-20 miles. Often the light will go out on its own. I know, it's the most dumb thing ever to associate with an "Engine Service Soon," but it's really easy to do with newer gas caps (slightly cross-thread or misinterpret the cap is closed.) The OBD codes for a leaky gas cap are misleading and this happens a LOT, especially if you've recently gotten gas.

    - Make sure your car/truck/interstellar space craft **is** an OBD II. Older vehicles will be OBD I and they are not interchangeable. Our 98 Cabrio is an OBD I and this scanner is an invaluable tool in the arsenal in keeping it running clean and lean.

    1 reply

    Correction: It was my Toyota pickup that was OBD I, the Cabrio is indeed OBD II. Sucks getting old. :-P

    I have had one of these for ages and it cost me more like $20.00 on eBay. It scans the error codes and asks Erase Yes/No.

    Job done in 28 seconds.

    One thing I have not seen mentioned in the comments is ABS codes or airbag codes. Most of your cheaper OBDII scanners will only read the engine codes. Engine light is an indicator for multiple vehicles systems but not ABS or airbag. These systems have separate modules which take a more pricey scanner to read. If you are being charged $75 dollars for a shop to read your codes you're being robbed. Most auto part stores will read the code for you for free. We do not charge to read codes at my shop. In fact you're not charged unless we find and fix the problem. There are plenty of shops in the industry that give people like myself a bad name. I got into automotive repair because I'm good with my hands and I wanted to help people. It's not for the money. Mechanics make a starving wage. Most of the money you are forking out does not even see the mechanic. Keep that in mind when you go to pay your bill.