Speedometer and odometer not working - engine light on - code P0502

[raynon2]

Hello, (this is on a 2008 aveo - 5spd trans.)

So about 2 months ago my speedometer stopped working just after driving down a really rough dirt road. Then I pulled into a wal-mart a few minutes later and when I left it came back working fine. It worked seamlessly for the next 3 weeks. Then, as I drove out my driveway one day about a month ago, it stopped working again. Each time it has stopped working, the odometer has also stopped recording mileage.

On a side note, not sure if this could be related, but the exact same day the speedometer stopped working for the second time, my fuel gauge also began to read inaccurately. It will "stick" in one spot, say 3/4 for hours of driving on the highway, but as soon as I slow down or come to an abrupt stop it will come way down to where it should be or sometimes lower than it should be. But then, as I accelerate again, it will go back up displaying more than I know I have in the tank. It does this, but in relation to how much I actually have. So if I know I have less than a 1/2 tank it won't go back up to 3/4 so I can know, with some certainty, how much fuel I have, but it is erratic.

My main issue, of course is the speedometer. It did set a code - P0502 - "VSS circuit low input". Also, the first time the engine light came on it idled very rough - increasing and decreasing idle speed from 500rpm(almost stalling) would jump up to 1500rpm and just keep going from stalling to reving up to 1500. But after I cleared the code that day it has never had a problem idling even though the light has come back on. weird right!?

Any help is appreciated. I'm taking a guess at the VSS as the one at fault. Maybe it got jossled around and broke when I was on that rough road, but then it just took a while before it completely gave up. Who knows.

Thanks!

[thankful_ragamuffin]

I'll venture that you have two problems - a bad VSS and a bad fuel sender.

[camopaint0707]

yep, the speed sensor is probably bad

[MotorCity]

had this happen to me, had to replace coils for $500