I bought my 2005 4-door aveo in the summer, and had no issues other than the damn car alarm going off randomly for no apparent reason (which I now know a lot of people have this issue, great job Chevrolet). Now though, whenever it's cold outside and I go to drive my car, it won't switch to the third gear (around 50km/h) until the engine heats up. I took it to a transmission place and they put a really expensive OBD reader to it once it was left outside in the freezing cold one night.. only to find that the scanner came up with no errors. They suggested it was a component in my engine exposed to the elements which tells the computer system in my car what gear it's in and when to switch (he told me this only by driving my car in the cold btw). He said that Chevrolet doesn't carry this part in their inventory and that total cost would be $500 to fix and it wasn't a "guarantee" fix. I have looked at other threads and posts to this issue but none seem to fit exactly to what I having issues with. No garages or transmissions places I have been to have ever experienced or even heard of this problem. Has anyone here had this problem with this or any gear in their car when it's cold or not? It's super frustrating because I have to drive my car around to heat up before I can take it on the highway or else it will rev to 3,500+ rpm at 80-90 km/h putting ware and tare on my vehicle, also wasting a ton of gas. This problems even happens now when it's slightly cold outside and has been sitting out all night.
Anyone insight or help, please let me know. I'd like to get this fixed before next winter.