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

[Tom W]

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)

BJamesjr@aol.com wrote:
> 
> > 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.