[Shotimes] Re: Why does the CE light go on if the gas cap isn't tight on OBD II cars?

[Kevin & Cheryl Airth]

This also happens on the earlier OBD I cars. Unscrew the gas cap and start
driving. You will get a check engine light.
.
.



> On OBD2 vehicles there is a monitor function that tests the fuel system
> evaporative emission integrity. If you leave the gas cap loose or refuel
> the car with the engine running, it may turn the MIL on and set a code.
>
>            Tom W
>            Red 93 ATX
>            Black 92 MTX
>            Both OBD1 (thank God)

> >
> > > When you went in for an emissions inspection they used
> > > to remove your gas cap and test the cap to see if it
> > > were working properly.  Since (at least here in GA)
> > > cars with OBDII supposedly know if your car is working
> > > right, all they have to do is plug into your cars OBDII
> > > port and the car will tell the examiner if it will pass.
> >
> > In selected high-pollution areas here in Texas, they do both.  They plug
into the OBDII port and interrogate the computer, AND they do some sort of
pressure test on the gas cap.