# Blinking Check engine light **URL:** \ **Category:** Factual Questions\ **Created:** [June 4, 2012, 12:39pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022 "2012-06-04T12:39:37Z")\ **Posts on this page:** 20\ **Page:** 7
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [June 12, 2012, 1:58pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/121 "2012-06-12T13:58:41Z")
Are newer cars these days doing more than just flashing a CEL? It seems that with the advent of LCD screens and robust user interface they could practically give you the code and problem description right on the screen without much difficulty at all. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [June 12, 2012, 2:23pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/122 "2012-06-12T14:23:16Z")
> [@Cheesesteak](#): > > Are newer cars these days doing more than just flashing a CEL? It seems that with the advent of LCD screens and robust user interface they could practically give you the code and problem description right on the screen without much difficulty at all. I’m sure they could, but I can see a number of complications. They’d have to add software/hardware equivalent to a code reader, at additional expense. Although some consumers would love to have that, many don’t particularly care – they’re not going to fix it themselves, anyway. As mentioned, just having the codes doesn’t necessarily tell all that’s needed (in fact, usually don’t) to get to the bottom of the issue. Data readout (at additional complication and expense) could enhance that, but for the overwhelming majority that would be a lot of info that makes very little sense. It might be like getting complete blood workup results, in that a physician can gather a lot of useful information from it but a layman is not likely to get much good out of it. On the human psychology side, we in the repair field would probably prefer not to have a lot more folks presenting us with what they think is wrong, not because we don’t want them to know, but because they usually don’t really know what they think they know. All things considered, I doubt there is enough benefit to justify the costs. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [June 12, 2012, 2:38pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/123 "2012-06-12T14:38:08Z")
> [@Cheesesteak](#): > > Are newer cars these days doing more than just flashing a CEL? It seems that with the advent of LCD screens and robust user interface they could practically give you the code and problem description right on the screen without much difficulty at all. Yes, while they will not give the exact code, some cars will give a more user-friendly description of the problem Other cars have some sort of diagnostic mode, usually hidden, that gives various sensor readouts, for example [http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics](http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics) I am not aware of a car that will show the actual trouble codes though. ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [June 12, 2012, 2:45pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/124 "2012-06-12T14:45:10Z")
> [@Gary\_T](#): > > I will rescan for free within 30 days, and agree/hope Firestone should do likewise. > > They will rescan. If it is a different problem they will tell me so, but I will have to pay another $100 to find out exactly what. > > The OBD-II doesn’t make it more expensive, assuming you mean more expensive than doing an analogous repair on older vehicles. It’s the overall design that makes it more expensive, in this case having one ignition coil per cylinder rather than a single coil for the whole engine. Of course with the single coil, it was necessary to have a distributor and spark plug wires, which represent potential repair expenses that you will not have on your car. > > Well, obviously you don’t. 🙂 But please consider this perspective: As I mentioned, it’s the overall design that leads to certain repair situations and expenses. One goal of this design is to control/minimize tailpipe emissions, for the public good. But along with that goes enhanced performance, better fuel mileage, and better overall reliability. “Back in the day” it was necessary to replace points and spark plugs approximately every year, 10-15K miles, and it wasn’t unusual to need to adjust points and clean plugs between replacements. Now, electronic ignition components give trouble-free performance for years. Replacing coils after 200+K miles compares rather favorably with replacing points 15-20 times during that same period. Spark plug replacement intervals are at least 30K miles, with more and more vehicles it’s 60-100K miles (depends on the particular plug design used). > > Your point is very well taken. I have repeatedly said that they do not make cars like they used to, thank god. I used to be astounded if I had a car turn over to 100K. Now that is the break in system. > > The OBD-II system is the controller and watchdog of the overall design here. Blaming it is rather like killing the messenger. Aside from its annoying use of the CEL, it does a remarkable job of keeping everything working smoothly and efficiently. Your mention of “nothing wrong” might be more accurately rendered as “nothing wrong that has to be fixed for my car to run acceptably.” > > I was trying to come up with a phrase that exactly what I felt. You have done a good job at doing so. > > However, there is something wrong in terms of some polluting being done, and the cumulative effect of that little bit of polluting multiplied by millions of cars over many years really does add up. It can be hard to really grasp how much public good has been done by cleaning up car exhaust because we haven’t experienced how awful it would have been if the U.S. had not enacted pollution controls. One might look at the situation in China to see what we have been spared. You and your loved ones have benefited from this. I disagree that keeping your car in spec is unfairly punishing you while doing no good. As I have said, I believe the initial considerable expense I encounter just paying for the original equipment is enough many to spend. If these things then wear out and break I do not feel it reasonable to keep pouring money in. I feel that I have tried very hard to help the air, but that I have done enough. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [June 12, 2012, 2:46pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/125 "2012-06-12T14:46:38Z")
**Gary T** , the car already knows the trouble codes, it doesn’t need any extra hardware, all needed is a few extra lines of code and it would be possible to show them on the LCD. The reason car mfgs do not do that is the same reason there isn’t by default an event viewer shortcut on the desktop of your Windows computer. It will only confuse users and nothing good can come from that! ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [June 12, 2012, 2:50pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/126 "2012-06-12T14:50:01Z")
> [@dauerbach](#): > > As I have said, I believe the initial considerable expense I encounter just paying for the original equipment is enough many to spend. If these things then wear out and break I do not feel it reasonable to keep pouring money in. I feel that I have tried very hard to help the air, but that I have done enough. Fair enough, I can see your point. We don’t agree, but we don’t have to agree. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [June 12, 2012, 2:51pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/127 "2012-06-12T14:51:13Z")
> [@Dog80](#): > > **Gary T** , the car already knows the trouble codes, it doesn’t need any extra hardware, all needed is a few extra lines of code and it would be possible to show them on the LCD. > > The reason car mfgs do not do that is the same reason there isn’t by default an event viewer shortcut on the desktop of your Windows computer. It will only confuse users and nothing good can come from that! I believe you’re quite right about that. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [June 12, 2012, 3:00pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/128 "2012-06-12T15:00:37Z")
> [@Dog80](#): > > Yes, while they will not give the exact code, some cars will give a more user-friendly description of the problem > > Other cars have some sort of diagnostic mode, usually hidden, that gives various sensor readouts, for example [http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics](http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics) > > I am not aware of a car that will show the actual trouble codes though. My car has about 4 pages worth of messages and message/warning light combinations listed in the owner’s manual. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [June 12, 2012, 3:04pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/129 "2012-06-12T15:04:29Z")
> [@dauerbach](#): > > As I have said, I believe the initial considerable expense I encounter just paying for the original equipment is enough many to spend. If these things then wear out and break I do not feel it reasonable to keep pouring money in. I feel that I have tried very hard to help the air, but that I have done enough. If you don’t want to pour any more money into, get a new one. With over 230,000 miles, this one has given you more than your money’s worth. I don’t know what you are whining about, a car is just a machine and will break down eventually. That’s what machines do. How you thought it would run forever without breaking down is beyond me. ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [June 12, 2012, 3:23pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/130 "2012-06-12T15:23:46Z")
> [@Kimballkid](#): > > If you don’t want to pour any more money into, get a new one. With over 230,000 miles, this one has given you more than your money’s worth. I don’t know what you are whining about, a car is just a machine and will break down eventually. That’s what machines do. How you thought it would run forever without breaking down is beyond me. I never thought it would run forever. I am absolutely delighted with the service it has provided me. However, and for this you must read my lips, THE CAR IS NOT BREAKING DOWN. It needed two ignition coils after all those miles. Now, the mindless government regulators say that, because my car is emitting more pollutants than it should I should be forced to take it off the road and go to a hefty expense to replace it. That is what I am bemoaning. That morons are trying to convince me there is something wrong with this car. ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [June 12, 2012, 3:47pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/131 "2012-06-12T15:47:42Z")
> [@dauerbach](#): > > . . . because my car is emitting more pollutants than it should I should be forced to take it off the road and go to a hefty expense to replace it. . . . Don’t you feel obligated to do your part for clean air? Fix it or euthanize it. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [June 12, 2012, 3:53pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/132 "2012-06-12T15:53:47Z")
When this is happening: > [@dauerbach](#): > > my car is emitting more pollutants than it should You can bleat and sputter all you want about the expense, but: > [@](#): > > there is something wrong with this car. ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [June 12, 2012, 6:02pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/133 "2012-06-12T18:02:03Z")
First, I absolutely do not feel the least bit obligated to spend thousands on a 10 year old car so there can be infinitesimally less pollution in the world. Second, there is nothing wrong with the car. It might pollute more than it was optimally designed to do. If I bought so that I could pollute as little as possible I would never turn it on. I purchased it for transportation, that desire does not make me responsible for the entire biosphere. Get a) a life or b) a brain. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 12, 2012, 6:17pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/134 "2012-06-12T18:17:28Z")
> [@Dog80](#): > > Yes, while they will not give the exact code, some cars will give a more user-friendly description of the problem > > Other cars have some sort of diagnostic mode, usually hidden, that gives various sensor readouts, for example [http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics](http://www.carandimage.com/forums/showthread.php?2080-VW-Golf-mk-V-Hidden-computer-diagnostics) > > I am not aware of a car that will show the actual trouble codes though. Chrysler cars and trucks will give you powertrain trouble codes (P-codes) right on the odometer display if you turn the key from ACC-RUN and back three times. > [@dauerbach](#): > > Second, there is nothing wrong with the car. It might pollute more than it was optimally designed to do. then there’s something wrong with it. That you don’t believe what’s wrong with it to be terribly important is immaterial. ---
**Author:** ![Willcross](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Willcross](https://boards.straightdope.com/u/Willcross)\ **Post date:** [June 13, 2012, 3:03am UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/135 "2012-06-13T03:03:25Z")
If the MIL is on, then the vehicle is not working as it was designed to. That by definition means there is something wrong. Technicians can not predetermine what is important and not important to a customer just by looking at them. Therefore, it’s important to let you know everything that is not working properly and let you make that call. They supplied you with that info, and you chose not to follow up on it. I don’t understand why your upset? ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [June 13, 2012, 12:13pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/136 "2012-06-13T12:13:34Z")
I am upset because this great car that I have is now causing me large expenses not because of any problem that affects its drive ability, but rather due to government regulations that I feel have gone way over the top. I feel that most repairs related to the obdc-II cause me significant detriment (cost lots of money) and give me absolutely no benefit. That the government is making me throw money away under threat of no longer allowing my car to be on the roads. ---
**Author:** ![SmellMyWort](https://avatars.discourse-cdn.com/v4/letter/s/ea5d25/32.png) [@SmellMyWort](https://boards.straightdope.com/u/SmellMyWort)\ **Post date:** [June 13, 2012, 5:09pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/137 "2012-06-13T17:09:14Z")
> [@dauerbach](#): > > I am upset because this great car that I have is now causing me large expenses not because of any problem that affects its drive ability, but rather due to government regulations that I feel have gone way over the top. I feel that most repairs related to the obdc-II cause me significant detriment (cost lots of money) and give me absolutely no benefit. That the government is making me throw money away under threat of no longer allowing my car to be on the roads. BS. When you started this thread you said the car “idles slightly roughly and my MPG has plumeted.” Do those things not affect the car’s driveability and your pocketbook? Having a car that runs well and gets you the most MPG doesn’t beneift you? You mentioned you drive 200 miles a day; even a 5 MPG drop will cost you over a thousand dollars more in gas over a year. You seem all too eager to blame the government and Firestone for your car-related expenses, but the truth is that if you’d maintained your vehicle properly and maybe educated yourself a little about your car you might have avoided setting off the problems that eventually damaged your coils and cat. And when you really think about it a couple grand over 10 years and 200K+ miles isn’t much, especially if it’s going to give you another few years. So to answer your question from yesterday, yes, I feel the “harm” done to you personally is FAR outweighed by the system we have in place. ---
**Author:** ![dauerbach](https://avatars.discourse-cdn.com/v4/letter/d/c2a13f/32.png) [@dauerbach](https://boards.straightdope.com/u/dauerbach)\ **Post date:** [June 13, 2012, 6:19pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/138 "2012-06-13T18:19:45Z")
I thought I had made myself clear, evidently not. Replacing the ignition coils was done 5 days after the symptoms presented. I have no complaint about that repair. At that time the car was broken, I took it in, it is now fixed. My complaint about that whole experience was the fact that I knew it was broken, the CEL added no information I could use, and I felt that had that light not come on I would not have been charged a $100 fee for the diagnosis. Prior to that the CEL had been illuminated for almost two years. The cat converter was dead. The dead cat converter had no effect on the car as far as I was concerned. Three days after the ignition coils were replaced the CEL illuminated again. Firestone said they would run the diagnostics again with no charge unless the codes were different. They likely are, since the car runs just fine now, with excellent gas mileage. My best guess is that by driving around 400 miles with the CEL light blinking the cat converter was poisoned. I won’t need to get emission inspected again for two years. You are correct. I have a car with over 231K miles because I am a dolt who doesn’t maintain their car. What in what I have said leads you to believe I have caused my own problems with this car? Except perhaps the latest CEL illumination. Believe me, I had LOTS more important things to do than worry about that light. Perhaps you should home brew less and read more carefully. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 13, 2012, 6:24pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/139 "2012-06-13T18:24:30Z")
> [@](#): > > I thought I had made myself clear, evidently not. You _did_ make yourself clear. We’re just telling you that you’re wrong. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 13, 2012, 6:38pm UTC](https://boards.straightdope.com/t/blinking-check-engine-light/624022/140 "2012-06-13T18:38:23Z")
> [@dauerbach](#): > > You are correct. I have a car with over 231K miles because I am a dolt who doesn’t maintain their car. What in what I have said leads you to believe I have caused my own problems with this car? er… > [@dauerbach](#): > > My best guess is that by driving around 400 miles with the CEL light blinking the cat converter was poisoned. > [@dauerbach](#): > > However, since the plugs have never been changed [Previous page](https://boards.straightdope.com/t/blinking-check-engine-light/624022.md?page=6) [Next page](https://boards.straightdope.com/t/blinking-check-engine-light/624022.md?page=8)