marble sound + speed sensor?

ok last night i finally got to put a timing light on my car, everything was great it was running smooth. Today on my way home from school the check engine light came on, so i shut the motor off and pulled to the side and looked under no overheating or anything unusual ( i checked for overheating because my temp gauge is broken :disappoin ) so i checked to see what the ecu was trowing out, code 17... i waited like 10 mins. then started it back up and was continued going back home,
and it happend agian so i did the same thing. ( i didnt know what a code 17 was while i was in the car) Then on my way home AGAIN something i thought i would never have to hear agian happend it sounded like a marble flew thu my exhaust
good think i was only 150 feet or so from my house..

My question is what could this mean? my timing is perfect now...maybe some how the speed sensor (code 17) and the marble sound have somthing to do with each other?? or just a Coincidental :screwy:

you might want to try to raise the idle up,
I've had a few episodes from too low idle,check engine light will come on,
& ecu will show code 17,
even thou my idle wasnt low,
it was just the only thing I messed with before it happened,
I was freaked out the first time it happened to me,
but about the marble thing,
could of been a bolt or could of been your heatshield?/?(i dont know)

does the code come back if you reset the computer?

speed sensor borken?