"Lady via CarKB.com" <forum@CarKB.com> wrote in message
news:fba1f72ffd944eafa6f0d3d6e3f1664d@CarKB.com...
> Ok, I totally admit I might be way off, but that's just what happened the
> last time, so I figured that'd be it now, too..
> BTW, what is a OBDII? Please excuse my ignorance, but hey, don't give a
> girl those big words she can't understand! (I'm still in kindergarden
> when
> it comes to cars, ok?).
>

Don't be embarassed - we tend to forget acronyms like OBDII are jargon.

OBD stands for "On Board Diagnostics." It is a standard for a maintenance
interface to the Engine Control Unit, the computer that controls the fuel
injection, ignition and related engine stuff. Since 1996 all cars sold in
America have to comply with level 2 of the specification, which gives us the
"II" (pronounced "two.")

OBDII is the Citizen Kane of the power train - always there behind the
scenes making sure the emissions are right. Yep - the specification exists
to control emissions (although Honda and some other manufacturers have
piggy-backed transmission codes on it). If it sees something is wrong, it
turns on the "check engine" light to tell you something is wrong and you
can't tell what it is! Brilliant plan there. If you leave the gas cap loose,
the "check engine" light comes on because the system says there is a vapor
leak. You can either take the car to the garage to have the codes read, or
buy a reader yourself, or wait to see if it goes away, but the car won't
tell the driver what is wrong - just "something." Gotta love it.

This brings up an important point. Unlike the oil pressure and battery and
coolant temperature warnings we are used to, as long as everything seems to
be working normally there is no reason to stop driving when the "check
engine" light comes on. The worst possibility is that the engine has lost a
sensor that is now causing the mixture to be too rich, and hard driving -
like charging up hills on the freeway - can damage the catalytic converter.
As long as everything seems normal, you can gently drive a car with the
"check engine" light on forever without hurting it. If the fuel economy is
reasonably normal, you can pretty much ignore the "gently" part, too.

Mike