If you grew up in "my day" you knew that when the engine light went on in your car it was something serious. Ruptured cylinder, exploding piston, melting transmission, fire in the glove box, the Russians launched their ICBM's.
Then something happened around the mid 90's.
The horrible and much-feared engine light would go on, and after a gallon of adrenaline shot through your body, praying the car wouldn't blow up with you in it on the interstate during rush hour, it magically made it safely to the nearest and most-rip-offish service station. The next day you picked it up and found out "eh, oxygen sensor. 100 bucks to reset the code."
Next car, engine light, panic, station, 100 bucks "fuel sensor."
Next car, engine light, "what the F&CK? Again???" mild panic, drive it around a little more, station, "fuel sensor" 100 bucks.
Next car, engine light, "f#ck it, don't care." Drive around for another 6 months, pull into an auto part store and the clerk tells you "yeah, if you give us your ID, we can lend you this plug in device to your dashboard and it will reset it for you. You walk out, WOW! Who knew! O2 sensor! Reset button, NO 100 bucks.
So in 15 years the much-feared engine light, which was essentially X-Box's "the ring of death" for cars, no longer says a damn thing about your actual engine, but whether or not your exhaust indicates the TIPPY TOP MOST SUPER EFFICIENT mix of air and gas.
Is it vital?
Is it even important?
But unless you run the damn diagnostic on the car, you never know if THIS ONE TIME it ISN'T the bleeping oxygen sensor and the car is about to blow up and render you a charred corpse on a traffic jam during rush hour.
Now, it isn't as bad as in the mid 90's when the local station would charge you $100 to plug something in and hit a button, but you still have the fear of an imminent exploding car and the annoying chore of driving to your local O'Reilly's Auto store to use your license as collateral to boring a plug in device. And so when your beloved ole Captain was driving early this morning, and received the deceiving "engine light" on his car, only to find out it was once again the stupid "fuel sensor" he went online and bought this.
Not only will I save enough in gas to pay for the damn thing, I will also increase my life expectancy by 40 years not fretting about the stupid check engine light.