Strange question about the fuel cap

[Kilroy]

What are the odds, that on a 1999 Alero with the 3400 V6, that I could drive 25oKm with the gas cap left off, and NOT have the engine throw a code?

The reason I ask, is that I drove that distance from fueling up, to the place I stopped at, and the next day I noticed the gas cap hanging on the fuel filler door. I am wondering if someone tried to siphon gas or I just plain old forgot to replace the gas cap after refueling. By the way, it would of been all highway miles.

If someone DID try to siphon gas, they didn't get any, cause mileage wise thee was no gas missing. ???:wacko:

[CactusWill]

Would you have preferred the dummy light come on? :p

[Kilroy]

Would you have preferred the dummy light come on? :p

YES!!!

[misslindseysue]

Evap codes are set based on a number of conditions being met. If you drove that far in one day it probably wouldn't set. You generally need a couple days to set a gas cap (large leak) code because it needs a long soak period to try to pull a vacuum and then not see it.

[guiguilandry]

actually it need 3 ''drive cycles'' to set this codes. By drive cycle they mean warming up the engine, rolling a certain amount of time in certain conditions and stopping the car to let it cool down.. x3