Check Engine Light PO700 and others, car isn't shifting into Overdrive

so my aveo, 2004 with 75000 miles, has started messing up. here's the story, i stopped and got gas, drove down the road, check engine light comes on, and the car just starts shifting really weird. so i pull over and tighten the gas cap thinking that is the problem, nope. well i'm driving down the road and the car pulls out and shifts immediately at around 2000 rpms, and then again at 2500 and thats it. I'm driving like 60-65 mph pulling around 4000 rpms the entire way to town. i stop at advance auto and have them scan the codes, PO700, transmission system malfunction, and there were like 6 other codes, too, 4 of them were emission related and the other ones i cant really remember, but one was something like "Throttle position range sensor" or something like that. I get on google and do a search and there are a couple other aveo owners experiencing the same thing and one guy suggested he replaced the Park/Neutral switch, which cured the problem while others said there was a TSB that chevy released with the PO700 codes stating that it was an "engine valve seal problem". any clue what exactly could be wrong, i'm taking it to my mechanic thursday and i just dont know what to expect. thanks

Maybe something to do with the throttle body, or a valve or valves are toast, do you drive the car hard, or always take it easy with it?

I'd say the throttle positioning sensor is the problem. But without having the car and all the codes it's hard to diagnose.

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Originally Posted by ontarian_frog

I'd say the throttle positioning sensor is the problem. But without having the car and all the codes it's hard to diagnose.

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i agree, the transmission wont know when to shift if it doesnt detect where the gas pedal is. Also not knowing where the gas is will cause all kinds of emissions issues. I believe there is a TSB on the Throttle body related to this? or at least about the throttle body.

but with that number of codes and not knowing them, one of those codes could point you in a totally other direction.

hey thanks for the replies, as far as the Throttle Position Sensor, where is that located and what am i looking for exactly, i'm clueless when it comes to really technical stuff about my car. I'm probably going to exhaust all the "inexpensive" options to try and fix it before i take it to a dealership to let them run diagnostics and crap. I saw online where I could buy a sensor for like 40 bucks. I'll try that first, then maybe the Park/Neutral Selector switch ( i spoke with my mechanic today and he suggested that that may be a the problem too, because when I put the car in drive and park, it jerks really hard). But if i could get some help as to what i'm looking for, perhaps if someone could grace me with a picture of the engine showing me exactly what is it, that would be very much appreciated. thanks

the sensor is part of the throttle body.

Number 33 (it's on the throttle body).

http://gm.ws123.net/EN/documents_200...n.html#T1F0CL3

so its on the backside of the throttle body?