I was driving home from work the this past week, and as I was topping a hill on the freeway the dashboard lit up with some ominous error messages about my engine. Next, the check engine light came on.
I was able to get home without issues, but I was assuming that I would need to bring the car in to get it fixed.
Before I went too far, however, I went online to do some research on the specific issue my car was having.
Some others had mentioned that some relatively cheap fixes for the problem, but they suggested checking the OBDII fault code that caused my check engine light to come on. If it was the same code, it might be worth it to try and fix it on my own. It might even be something I didn’t need to fix.
I’ve had my car diagnosed before where they hook the car up to a scanner, find a fault code and then tell you what is probably wrong with the car. Every time I’ve done that, however, it has ended up costing me $75-100 just for them to hook the car up to the scanner. While I was online diagnosing the problem, I came across some articles that told how you could just read the OBD-II codes yourself, and figure out what type of a problem you have. Often the fault codes will lead to relatively minor issues like a loose gas cap, or may point you in the direction of your car needing service with a certified mechanic.
Before I made an appointment I decided to get my car scanned to find out what the fault codes were that were causing the light to come on. If it was this same issue that I had seen online I might be able to fix the car myself and save myself hundreds of dollars. If not, I’ll at least save myself the $100 diagnostic charge.
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What To Do When Your Check Engine Light Comes On
When your check engine light comes on, it’s important to get it checked out right away.
The light could be an indication that there is a serious problem like a major engine issue (that could be a safety issue), or it could be something simple like tightening your gas cap (which my wife had to do one time). The point is, until you get it checked, you just don’t know. So get it checked.
Here I am checking the engine fault code recently using a Bluetooth dongle and my Android smartphone:
Common Reasons For A Check Engine Light
So what are the most common reasons the check engine lights come on? AutoTrader gives the 5 most common reasons:
- Faulty O2 sensor: The oxygen sensor measures how much fuel is being burned and whether it’s too little or too much. Around $200 to fix according to AutoTrader.
- Loose or damaged gas cap: Usually fixed by getting a new gas cap. Easy fix, usually $20-30.
- Bad catalytic converter: Costs an average of $2000 to fix. Pricey, let’s hope you don’t have this one.
- Problem with the mass airflow sensor (MAF): Could cost an average of about $375 to fix.
- Spark plug problems: The fix can range from $20 for someone who can DIY it, or quite a bit more at a shop. If you neglect this one, it could lead to problems with the catalyic converter, which you don’t want since it’s pretty expensive.
OBD-II PID Diagnostic Codes
All light-duty vehicles (less than 8,500 pounds) sold since 1996 in the United States have on-board diagnostic systems (OBD-II – on board diagnostics version 2) that diagnose when your vehicle has certain power-train, emission and other readings that are out of accepted ranges. When the diagnostic system finds a problem, it outputs a OBD-II code, also called a PID (Parameter ID), that can be read by a OBD-II scanner.
To get the code you just connect your OBD-II scanner to the data link connector, typically found under the driver’s side dashboard of the vehicle.
Once the scanner is connected it will read a PID code that can then be used to help diagnose what your issue might be. Once you have the PID you can go online and see what the code means. For example, Wikipedia has a listing of PID codes you can check out.
Where To Get It Checked
When trying to find out what tripped your check engine light, there are quite a few ways that you can check what the trouble code is. Some of the ways will even be free.
At a local auto parts store
Most auto parts stores will have an OBD-II scanner on hand to check the OBD-II PID service codes, and will do it for free. I’ve called several stores in my local area, and all of them said they will scan the codes for free. Why do they do that? They’re hoping you’ll be a DIY fix-it type, and will buy the parts to fix your problem through their store. Seems like a good idea on their part. Here’s the ones in my area that I verified.
Your best bet is to just find a local auto parts store and give them a call- and verify if they will do a scan for free. Typically they’ll do the scan, figure out the codes and then give you a list of things that might be causing the problem. Be careful, however, because if it is a vague issue you can quickly spend more on parts trying to fix an issues, than if you had just gone to a mechanic in the first place.
Check the codes yourself
You can quite easily check what your PID fault codes are yourself. All you will have to do is buy a cheap OBD-II scan tool, and then look the codes up online.
Here are a couple of cheap tools to do it:
- Bluetooth OBD2 Scan Tool for Android: Connect this device, then open an app like Torque Pro on your Android tablet or phone, which connects to the device via Bluetooth. You can then get the codes, reset the check engine light, along with a host of other things.
- WiFi OBD2 Scanner for iPhone: This scanner plugs in and then connects to your iPhone or iPad via WiFi to get codes. To be used in conjunction with an app like Dash Command to get the codes and reset the lights.
- OBD-II Scanner: This tool doesn’t require a phone or tablet, it just checks and reports the code for you on it’s built in screen.
Once you get the PID code from whatever device you use, just look it up online to see what your issue could possibly be related to.
Go to your local mechanic
Your local mechanic may do a scan for you free of charge, especially if you already have a relationship with them. Often they’ll also be able to give you more detailed information than you could get on your own, and be able to dig deeper into what’s going on with your vehicle.
I have a good local mechanic that I use when repairs are needed, and they have checked codes for me free of charge on occasion. They know that I’ll typically get any problems fixed through them since I trust them and they’ve been fair in their dealings with me in the past. If the problem diagnosis takes longer than expected, don’t expect it to be free, however. They do have to charge for their time.
Go to a dealership
To get more detailed diagnostics, or to get repairs that are covered by warranty you may have to go to a dealership. Dealerships will often have more expensive diagnostic equipment that has better and more regularly updated software, so they can often get you some of the best information. I have never, however, gotten them to give me a free diagnostic of what the problem might be. It usually costs me in the range of $75-100 or more. Again, they have to charge for their time, so if it is a more advanced issues you may have to pay.
Start With Your Free Scans, And Go From There
For me I think getting one of free scans at your local auto parts store is probably a good first step to take. It can give you some insight into the problem, and hopefully give you an idea if you need to pursue professional help. If you’ve got an older car that has had it’s fair share of issues, or if you just like tinkering, you might consider buying your own OBD-II scanner for anywhere from $15-100, which can give you insight any time you have a problem.
In the end you may or may not still have to go to a dealer or mechanic to get your car fixed, but at the very least you’ll have some good actionable information when you go in. If they then try to tell you it’s something completely unrelated you’ll know to ask more questions, or to get a second opinion.
My check engine light – no repairs required
So I went into my local Advance Auto Parts store and they did a quick scan, free of charge. They found that the fault codes on the on board diagnostics system were all related to when my battery died a couple of weeks ago. I’m not sure why the light didn’t turn on until now.
They reset the codes and the check engine light went out. They advised me to keep an eye on things over the next few days and weeks, and if it came on again to bring it back in. They can recheck it then and see if there were any other unrelated issues causing the light to come on.
UPDATE: My check engine light came on again today. After getting it checked at the auto parts store again, it turns out there was a throttle control sensor that was having problems. I took my trouble code into my trusted local mechanic, and he was able to confirm the issue and fix the problem for $150.
For now, I’ve saved myself a $75-100 fee at my local dealer to diagnose the issue. In the process of all this I also discovered there is a recall for my car for an unrelated issue, so I’ll be bringing it in to get that fixed at my dealer – free of charge.
Have you used your own scanner to diagnose a check engine light and find OBD-II PID codes, to try and diagnose your own issues and save some money? Are there times that you would rather just bring it in and pay?
Thank you Peter! This is super helpful and appreciated.
This article is great! I also had a similar experience with my check engine light and also am on a tight budget as a full time student. While trying to find a parts store near me that offers free services, I came across a site that shows the nearest auto parts locations to you (based on GPS) that offer free check engine light diagnostics. Check it out today:
http://www.checkenginefree.com
Hope this site can be as helpful as this article is to folks! :D
Awesome post Peter! I’ve come across one too many customers here in the UK who ignore their check engine light out of worry that they’ll face a massive bill if something big has gone wrong. It’s painful having to remind people that the check engine light shouldn’t be ignored- hopefully this will help a lot of drivers!
I don’t usually leave comments but this is an exceptional post, Peter, so I am this time.
Thank you for the information, details, and follow-up; you helped me very much.
As an employee of Advance Auto Parts I just want to inform folks that the company is going to stop reading engine codes and referring those who come in for that once free service to one of our commercial customers, in other words a garage. This has already started and will pretty much be a done deal by the end of June 2016. A few, and I mean a VERY few of these shops have said they would do the code reads for a nominal fee. Many of the shops want NO PART of it. Advance and other stores like them were started mainly for the DIY, er but some local shops are complaining that they are losing business by us offering this free service. I think the decision to stop providing this service is going to backfire on the company in a few ways. 1st, they are going to lose potential customers and sales from folks who WOULD have tried to fix the problem themselves. 2nd many customers come in for these code checks on weekends, evenings etc when local garages are not open. 3rd we are going to start pissing off our commercial customers who will have folks pulling their mechanics away from jobs they are already working on to do a free code read. They customer will either take that code and go home and google it and come back to Advance or another DIY store and buy the part or stay at the shop. The shop will then call one of these stores and order the part ( like a gas cap ) and the customer, who was just sent to the shop,since we now will not read their code ,will watch as one of our delivery vehicles pulls up and brings the part they would have bought from us to that shop and marks up the price. For larger more complicated issues I understand the reasoning for going to a professional but like I stated earlier Places like Advance, Auto Zone etc were started for folks who wanted to avoid paying a garage for something they may be able to fix themselves . I guess now that Advance has bought up most of their competition they feel there is more money to be made selling to the commercial shop than the DIY customer. I think this will blow up in their faces and will lose more business than they realize. I for one expect to see many pissed off customers and I will refer them to our corporate office.
I was shocked when a friend of mine went to Advance Auto Parts and was turned away after asking to have her engine light read. Instead, they should let the customer use the scanner themselves. After all, the store is for Do It Yourself (DIY) users. I agree, this will backfire into the face of corporation. I used to work for Advance.
The reason they are (and should) stop providing this “free” service is because vehicle diagnostics is not a diy project nor something that should be attempted by somebody without the proper training. For example, most of your late model vehicles (2010 and up) have over 30 different OBD codes that indicate an oxygen sensor problem. Of those 30+ codes not one of them actually means “hey, your oxygen sensor is bad”. Pulling codes is only the first step to a successful diagnostic. And yes… I’m one of those mechanics that is frustrated with the “free diagnostics” being offered at parts stores. Not because it cuts into my revenue but because I have to deal with the fallout when the “free diagnostic” was wrong and the customer had me install a part that didn’t fix their problem.
Well said Adam Hunsicker!
I am a Service Manager of a Technet shop (partnered with Advanced Auto).
This advice is like telling someone with a toothache to get some dental tools and a mirror and fix it themselves.
A small leak could be a gas cap or it could be a small crack in your fuel tank.
A misfire could be a spark plug. But do you know what brand is the ‘best’ for your specific car? Not the OE Design… but the actual brand. Yes, every car has a recommended brand.
A misfire could be a coil. Sorry you just spent $50 on spark plugs and the misfire is still there. Opps.. wasn’t a coil. Sorry you just dropped $150 for a coil. Now you are at $200 and your problem is still there. Oh what could it be??? Sure, go back to the University of YouTube and see what the “experts” say.
Or stop playing with something you are clearly not trained to do and let the professionals do their job.
If you come to the shop and ask me to put in new spark plugs, I will do as you ask. I make it clear that it might not solve your problem. I offer diagnostic testing, which is far different than an OBDII reading. If you decline, I will make sure to note that on the paper you sign.
Turns out the misfire was a bad fuel injector…. it would have cost you about $300 including a diag.. but because you decided to “throw parts at your car” (aka “throw grenades”) it now is going to cost you $500+.
God help someone that has a hybrid or electric car. This blog could easily kill them…. literally.
Cars today are getting less and less DIY and more and more DAYOR (Do at your own risk). Orange wires… NEVER TOUCH ORANGE WIRES. But folks don’t know that because they are not TRAINED.
It is one thing to be an informed consumer. But stop going to University of YouTube and Google Community College. If you want to learn about cars, go to a real school. Invest the hundreds of thousands of dollars that most technicians have invested in their education, tools and continued training.
Auto repairs have the LOWEST markup of darn near any industry. God forbid we make an actual living. One cup of coffee has about a 1000% markup on it. Repair orders are LUCKY to hit a 50% profit. The bigger the job, the LESS the shop makes.
Top it off with the way we are treated by our customers…. it is amazing that anyone even still wants to be in this industry anymore. I’ve called on Jesus more at work than I have ever had to raising four children. Let one more customer throw their keys at me and order up an oil change.
Let’s not talk about me being a woman in a man’s industry…lol.
Perhaps people wouldn’t try to find D.I.Y. ways of diagnosing their cars if so many mechanic shops (but mainly the big car brand companies) didn’t charge such high rates. I was told I had to pay $155 to get a quote from HOLDEN AUSTRALIA or GMH.
Karin Burton, I agree with you whole heartedly. I am a single mother of three children, and I am ALWAYS struggling to scrape by, no matter what I do. I have improved my income, just in time for out of pocket expenses and grocery prices to go up, and absorb anything extra I thought I was going to have due to the increase in income.
With that said, I cannot afford to pay a garage $155 to read my diagnostics and tell me that all I need is a new gas cap for $XX, that I now have to pay a total of $200 at the shop, when I could have spent $20 or less for at the DIY place. Hmmmm….$20 versus $200 = being able to fix the problem and pass emissions, versus not being able to do a darn thing and driving around on expired plates.
If, obviously it’s something that actually needs a mechanic, then I have to figure out what to do, and it usually has to wait until tax refund season in order for me to fix it. So, are DIYs REALLY causing so many problems? No. Why? Because, just as you mentioned Joann and Adam, if the DIY DOESN’T fix the problem, the customers are going to show up at your door regardless.
Don’t really see the issue here. Now, if shops like the ones Joann and Adam work at want to provide the Diagnostic for free, and the customer knows they can TRUST what the mechanic is telling them is the issue, and that they will fix it for the price quoted and guarantee the person will pass emissions, then I would just bypass the DIY and go straight there. Unfortunately, shops do not have a good reputation for being honest and trustworthy, and friendly.
Thank you Peter! This is a big help for me and the others. Continue to spread the love.
Hi. I have been using a home used 2012 corolla for a year. In the beginning full tank could show up to 400 miles which was a good consumption. But now I have been getting far less even 260 miles, indicating my consumption has increased considerably. I have purged the car and changed the plugs but still the problem persists. What could be the cause of my high consumption?
I just want to clear (extinguish) the orange coloured warning light, so do all generic scanners, including the cheap ones, have the simple capability to do this?
Getting rid of the unwanted light takes care of a legion of problems including the major one of a dealer or manufacturer racket or a bad contact in the sensor – computer -light circuit.
Wherever there is electronics there is fraud, including the major vw incident.
Went to reputable garage after serv eng light came on. They replaced fuel pump and a few additional parts. Cost over $800. Then light on again. Oops I guess it wasn’t the fuel pump. Code show small leak in evaporated system. Was told could be several things. So much for going to professional.
How do I find where my ode port is in 1997 Kia Sportage
I believe the OBDII port is under the driver side dash on that make/model – after doing a cursory search. Right above where the accelerator pedal is.
Thanks Peter,
When you see CEL (check engline light) is on , before to go to dealer or mechanic we should do somethings because some errors are easy to fix like air condition related (u-codes) or chasis related (c-codes) or sparg plug problems (p-code). But some how we need to go repair shop. i tried to list all obd codes on my business website for free with descriptions.
https://DtcFaultCode.com
May be someday you need check your fault code.
Have a nice days.
I have a bmw,320i,2006,2wd,sedan and the check engine light on the dashboard stays on.what does it mean?? I’ve tried screwing gas cap on tightly,put engine oil in engine,tyre pressure, it Neva used to have issues like the check engine light staying on, now it’ shudders wen I brake at intersections & sudden stops?it’s also loosing, using a lot of antifreeze & water,to the point where I have to fill it up every time I drive anywhere & the temperature gauge Icon on dashboard goes from a low 15¢ to 22¢