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This is not true. The check engine light can come on in some cars if the gas cap is not screwed on tight enough - easily fixed yet treated as serious as a major

This is not true. The check engine light can come on in some cars if the gas cap is not screwed on tight enough - easily fixed yet treated as serious as a major engine malfunction.

ams6110 12y ago
It can also come on for no apparent reason. Mine is on right now. Gas cap is tight, car is running fine. Starts right up, runs smooth, power is good, fuel economy normal. So I'm not going to take it into the shop. In this day and age we can have something more informative than a check engine light. Tell me what's wrong, or at least have a "verbose" option I can enable that will let me see WTF it thinks the problem is. I think the check engine light is a giant scam to get people to take their car in for service when there is nothing wrong with it.
- jschwartzi 12y ago
  My OBD-I truck had a pair of pins that, when shorted together with a paperclip, would read out the exact trouble code through the check engine light. As far as a verbose option, if you pull into an O'Reilly's or other auto parts store they will lend you, for free, an OBD-II scan tool with which you can read out the exact error plus any corresponding sensor data(freeze frame). If your check engine light isn't flashing, it's actually because your vehicle has detected an issue with your emissions equipment that means that the engine control module is not able to regulate emissions to within EPA requirements. There are various reasons why this could be the case, but it usually indicates an imminent failure. For example, mine is currently on because it's detecting a lean fuel condition in the cylinder bank when under high load, which means either that my fuel injection system is not able to keep up or that my throttle is letting too much air into the intake manifold. My car is still drive-able, but I definitely need to have it looked at because my fuel pump or injectors could be going out or my throttle could be faulty. The point is that it's not a scam, it's providing you useful, predictive information. You just need to know how to retrieve it.
- csours 12y ago
  Not exactly a scam. It means your car is not running optimally; generally it means it is polluting more than it should due to O2 sensor failure or backpressure from tailpipe.
- devicenull 12y ago
  You can buy an OBD-II reader for $8. It's cheap enough that the first time it tells you your gas cap was loose, it's paid for itself. So, for a trivial cost you can get your verbose option. Most people are not going to have any knowledge or desire to have this information, so it's a silly feature to include.
  - Someone1234 12y ago
    I purchased a Bluetooth one from Amazon ($10.99) and an Android app (Torque Pro, $5). Great tool for $16 all in. Plus the ODB-II adapter can be used to configure some "quality of life" stuff in newer cars (e.g. the constant cabin backup beep sound on the 2014 Prius). You will need an Android phone already, but these days that is pretty common (particularly for technical people). Just get the error code and Google it, it becomes pretty obvious what it is.
    - throwaway234 12y ago
      What tool do you use to change configurations? I know my 2007 Lexus has those programmable options like beep durations and such, but I have only found two solutions - paying the dealership $60 to change them, or buying a $15 android app that changes them. I could do it myself, but the codes (Lexus Personalized Settings) are secret. Did you find a free alternative to modify your Prius settings?
      - Someone1234 12y ago
        It is super easy on the Prius, this post goes through the steps: http://priuschat.com/threads/geniii-prius-custom-pids-for-torque-app.98693/ http://priuschat.com/threads/geniii-prius-custom-pids-for-to... But the short is someone else has done the hard work so you don't have to.
- joshmlewis 12y ago
  Never ignore check engine lights even if everything is seemingly ok. It could be a lot of different things, some harmless but some not so much. If it's something with a sensor or other intake part, it could also be taking away your gas mileage. Pro tip: As the others stated, they make good obd-2 readers for cheap and you can also go to many auto parts stores and they'll use theirs to give you the code print out for free.
- ToastyMallows 12y ago
  Not sure about your make/model/year, but my Check Engine light most likely means that I need an oil change.
aunty_helen 12y ago
Ok perhaps the example was a little off due to design abuse from some manufacturers. For example (I think) Alfa Romeo put the gas light on if the fuel cap is loose/missing. This is more of an appropriate design. (Unless it's a diesel then it really is a problem) The point that I was trying to address is that if there is a critical warning that you can't do anything about, there's no more info needed than 'stop and seek help' which is perfectly served by a simple light. Or do you want a 1 page problem statement to flash up on the dash and explain why you really need to pull over. The only reason you would do such a thing is if you wanted the user to make the evaluation of whether or not it is important or something that can be ignored.
- tbyehl 12y ago
  Manufacturers do not abuse the Malfunction Indicator Lamp. Its _legislated_ purpose is to alert the driver to issues which could compromise the emissions control systems of a vehicle. A loose gas cap causes a pressure leak in the EVAP system which captures fuel vapors from the gas tank.

This is not true. The check engine light can come on in some cars if the gas cap is not screwed on tight enough - easily fixed yet treated as serious as a major engine malfunction.

ams6110 12y ago

It can also come on for no apparent reason. Mine is on right now. Gas cap is tight, car is running fine. Starts right up, runs smooth, power is good, fuel economy normal. So I'm not going to take it into the shop. In this day and age we can have something more informative than a check engine light. Tell me what's wrong, or at least have a "verbose" option I can enable that will let me see WTF it thinks the problem is. I think the check engine light is a giant scam to get people to take their car in for service when there is nothing wrong with it.

jschwartzi 12y ago
My OBD-I truck had a pair of pins that, when shorted together with a paperclip, would read out the exact trouble code through the check engine light. As far as a verbose option, if you pull into an O'Reilly's or other auto parts store they will lend you, for free, an OBD-II scan tool with which you can read out the exact error plus any corresponding sensor data(freeze frame). If your check engine light isn't flashing, it's actually because your vehicle has detected an issue with your emissions equipment that means that the engine control module is not able to regulate emissions to within EPA requirements. There are various reasons why this could be the case, but it usually indicates an imminent failure. For example, mine is currently on because it's detecting a lean fuel condition in the cylinder bank when under high load, which means either that my fuel injection system is not able to keep up or that my throttle is letting too much air into the intake manifold. My car is still drive-able, but I definitely need to have it looked at because my fuel pump or injectors could be going out or my throttle could be faulty. The point is that it's not a scam, it's providing you useful, predictive information. You just need to know how to retrieve it.
csours 12y ago
Not exactly a scam. It means your car is not running optimally; generally it means it is polluting more than it should due to O2 sensor failure or backpressure from tailpipe.
devicenull 12y ago
You can buy an OBD-II reader for $8. It's cheap enough that the first time it tells you your gas cap was loose, it's paid for itself. So, for a trivial cost you can get your verbose option. Most people are not going to have any knowledge or desire to have this information, so it's a silly feature to include.
- Someone1234 12y ago
  I purchased a Bluetooth one from Amazon ($10.99) and an Android app (Torque Pro, $5). Great tool for $16 all in. Plus the ODB-II adapter can be used to configure some "quality of life" stuff in newer cars (e.g. the constant cabin backup beep sound on the 2014 Prius). You will need an Android phone already, but these days that is pretty common (particularly for technical people). Just get the error code and Google it, it becomes pretty obvious what it is.
  - throwaway234 12y ago
    What tool do you use to change configurations? I know my 2007 Lexus has those programmable options like beep durations and such, but I have only found two solutions - paying the dealership $60 to change them, or buying a $15 android app that changes them. I could do it myself, but the codes (Lexus Personalized Settings) are secret. Did you find a free alternative to modify your Prius settings?
    - Someone1234 12y ago
      It is super easy on the Prius, this post goes through the steps: http://priuschat.com/threads/geniii-prius-custom-pids-for-torque-app.98693/ http://priuschat.com/threads/geniii-prius-custom-pids-for-to... But the short is someone else has done the hard work so you don't have to.
joshmlewis 12y ago
Never ignore check engine lights even if everything is seemingly ok. It could be a lot of different things, some harmless but some not so much. If it's something with a sensor or other intake part, it could also be taking away your gas mileage. Pro tip: As the others stated, they make good obd-2 readers for cheap and you can also go to many auto parts stores and they'll use theirs to give you the code print out for free.
ToastyMallows 12y ago
Not sure about your make/model/year, but my Check Engine light most likely means that I need an oil change.

aunty_helen 12y ago

Ok perhaps the example was a little off due to design abuse from some manufacturers. For example (I think) Alfa Romeo put the gas light on if the fuel cap is loose/missing. This is more of an appropriate design. (Unless it's a diesel then it really is a problem) The point that I was trying to address is that if there is a critical warning that you can't do anything about, there's no more info needed than 'stop and seek help' which is perfectly served by a simple light. Or do you want a 1 page problem statement to flash up on the dash and explain why you really need to pull over. The only reason you would do such a thing is if you wanted the user to make the evaluation of whether or not it is important or something that can be ignored.

tbyehl 12y ago
Manufacturers do not abuse the Malfunction Indicator Lamp. Its _legislated_ purpose is to alert the driver to issues which could compromise the emissions control systems of a vehicle. A loose gas cap causes a pressure leak in the EVAP system which captures fuel vapors from the gas tank.