A gear which causes the transmission output shaft to rotate at a higher speed than the transmission input shaft.
If the transmission would not go into gear before changing the transmission fluid, then the fluid change was for naught. Hopefully you changed the filter in there, too. If the tranny was busted before the oil change, then simply changing the oil is not going to fix the problem.
low gear oil or gears are worn.
The clutch is slipping. try changing the transmission fluid. if that does not solve then prepare to either pay $1,500-$2,000 to have the transmission rebuilt, or buy a new vehicle
Poor driver or bad transmission.
Yes, changing gear ratios can cause an automatic transmission to not shift into the next gear if the new ratios are not compatible with the transmission's design or control system. This misalignment can lead to incorrect shift points or failure to engage specific gears. Additionally, if the changes are not calibrated properly, it can result in slipping or erratic shifting behavior. Proper adjustments and tuning are essential to ensure the transmission functions correctly with the new gear ratios.
The transmission control module has detected that the transmission is trying to mechanically shift to a lower gear than intended. Try dropping the transmission oil pan and changing the transmission oil and filter. If this does not fix it you will have to have it looked at by a mechanic.
If it will not go into gear you have probably missinstalled one of the filters.
If it's only when you attempt third gear the problem is in your transmission.
There are several causes that an automatic transmission will not want to shift into second gear. The two most common causes are transmission pump issues and trouble with the vacuum modulator.
Quite possibly a worn second gear clutch pack.
Make sure parking brake is fully released Transmission fluid and filter may need changing If it has a manual transmission, try giving it a little gas as you release the clutch into 2nd.