# Check Engine light **URL:** \ **Category:** Factual Questions\ **Created:** [February 7, 2003, 9:05am UTC](https://boards.straightdope.com/t/check-engine-light/153430 "2003-02-07T09:05:15Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [February 7, 2003, 9:22pm UTC](https://boards.straightdope.com/t/check-engine-light/153430/21 "2003-02-07T21:22:36Z")
> [@](#): > > \*Originally posted by sigung86 \* > \*\*Actually, if you have your car inspected on a regular basis, you can simply disconnect the check engine light. It has a plethora of input and only one output … Check Engine! > > For the most part, it is rinky-tink, at best, and a cool way for dealers to make money. > > Dan \*\* Actually, some of the components that cause the light to come on may affect your gas mileage substantially. Such as oxygen sensors. Leaving those unchecked can burn a hole in your pocket-book. …but, if you have the car checked often…Who does? ---
**Author:** ![LIONsob](https://avatars.discourse-cdn.com/v4/letter/l/76d3ee/32.png) [@LIONsob](https://boards.straightdope.com/u/LIONsob)\ **Post date:** [February 7, 2003, 10:24pm UTC](https://boards.straightdope.com/t/check-engine-light/153430/22 "2003-02-07T22:24:56Z")
I have a 96 Chevy Cavalier with OBD2 and according to the Chiltons manual I have for the car the troublecodes can be read without a scanner. What you have to do is jumper between 2 pins on the diagnostic connector located under the dashboard with a paperclip and turn the ignition key to on, the check engine light will start flashing out the various troublecodes. Long flashes = 10’s, short flashes = 1’s Example : 3 long flashes + 4 short flashes = troublecode 34 Hope This Helps Peace LIONsob ---
**Author:** ![Alien2022](https://avatars.discourse-cdn.com/v4/letter/a/e19adc/32.png) [@Alien2022](https://boards.straightdope.com/u/Alien2022)\ **Post date:** [February 7, 2003, 10:42pm UTC](https://boards.straightdope.com/t/check-engine-light/153430/23 "2003-02-07T22:42:28Z")
What if they had a reddish orange color…? Oh Hell… It’s red orange again… BOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMM!!!. ---
**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:** [February 7, 2003, 10:53pm UTC](https://boards.straightdope.com/t/check-engine-light/153430/24 "2003-02-07T22:53:10Z")
It is an OBD-II system. The trouble codes have five characters, a letter followed by four numerals. I know of no way to read the code memory without a scan tool. There are hundreds of possible codes. Some of the conditions that will turn the light on and set a code are relatively insignificant, while others are quite important. As a general rule, if there are no noticeable symptoms other than the light being on, it’s usually not an urgent or serious problem. However, it’s always wise to have it evaluated before too long. There’s just no way to know what’s going on without doing some testing. In the case of the OP, if you’re trying to avoid taking the car in for testing, the thing to try would be to replace the gas cap and clear the code memory (disconnect the battery). It’s not a sure bet, but there’s a reasonable chance there’s a problem with the cap. If it is something else, I would expect the light to come on again. There’s a world of difference between reading the codes and evaluating them. Many codes can be caused by quite a number of different conditions. Reading the code is often just the first step in figuring out what’s going on. If you want to really know what’s going on, take it to a competent repair shop. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [February 8, 2003, 12:18am UTC](https://boards.straightdope.com/t/check-engine-light/153430/25 "2003-02-08T00:18:25Z")
One thing to keep in mind if you go to a shop and they plug your car into a diagnostic system: the codes only tell the mechanic what device is sending the code. IT DOES NOT MEAN TO REPLACE THAT DEVICE!!! If the mechanic tells you this, pay him the diagnostic fee, thank him for his time and get the hell out. I had a diagnostic run on my car a few months after I got it (used) and the codes indicated that the oxygen sensors were sending the code. Turned out to be a vacuum leak. The mechanic was honest and told me he could have replaced the parts, but the problem would remain. As a cite for the above warning, see any of the car shows on TNN on Saturdays. ---
**Author:** ![SPOOFE](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@SPOOFE](https://boards.straightdope.com/u/SPOOFE)\ **Post date:** [February 8, 2003, 2:12am UTC](https://boards.straightdope.com/t/check-engine-light/153430/26 "2003-02-08T02:12:59Z")
[/quote] I had the same problem. After 3 weeks, the light went off. End of story. [/quote] Same thing here, but my car’s manual said that the “Check Engine” light can go on if you change brands of gasoline. It recommended that I wait until all the gas in the tank is from the same source before I take it in. After a few days, the light went off, and I haven’t had a problem since. ---
**Author:** ![sigung86](https://avatars.discourse-cdn.com/v4/letter/s/b38774/32.png) [@sigung86](https://boards.straightdope.com/u/sigung86)\ **Post date:** [February 8, 2003, 4:55am UTC](https://boards.straightdope.com/t/check-engine-light/153430/27 "2003-02-08T04:55:39Z")
Actually, like I said, the Check Engine light is a fell good ricky-tick kind of thing that makes money for the dealers. So much can mess with it that it is virtually useless to even indicate that you have a problem with your motor. If you are going to be blown away by it, then you probably should learn where your ALDL is, and where jumper a and jumper b are so you can pin across them and read the codes… Just some thoughts on a lazy Friday Night. LOL!!! C Y’all later. Dan ---
**Author:** ![Anachronism](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@Anachronism](https://boards.straightdope.com/u/Anachronism)\ **Post date:** [February 10, 2003, 12:50am UTC](https://boards.straightdope.com/t/check-engine-light/153430/28 "2003-02-10T00:50:23Z")
> [@](#): > > \*Originally posted by brad\_d \* > \*\*I don’t believe this is possible on newer vehicles. I want to say that OBD-II vehicles require the code reader (the count-the-flashes technique no longer works). Cars made after some date in the mid-90’s are of this type. > > Can somebody verify, correct, or amplify this? \*\* My car (98 Maxima) is OBD II and has a small switch you turn with a screwdriver on the side of the ECU, turn it once and you can count the flashes to check the code(s), turning it twice will clear the light. Of course the code will come back if you don’t fix the problem. It sounds like GM switched over to needing a code reader a little earlier though. [Previous page](https://boards.straightdope.com/t/check-engine-light/153430.md?page=1)