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.

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.

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.

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?

It is super easy on the Prius, this post goes through the steps:

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.

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.

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.

Not sure about your make/model/year, but my Check Engine light most likely means that I need an oil change.