From stop position, automatic transmission up shifts through gears at early stage, provided that the automatic transmission fluid is at normal level.
Check the automatic transmission fluid to make sure that it is on the normal level if not then this is causing the problem. A/T works on flows of hydraulic pressure, if the fluid level is not normal then a problem like this can be encountered.
However, if the fluid level is normal, then the possible problem is involving a faulty electronic sensor since the automatic transmission indicated on this problem is computer controlled. A/T shifts when a certain level of car speed and throttle position is reach, this was triggered by the data provide on the computer by the car speed sensor and throttle position sensor, since the problem is an early up shifts then one of this sensors might be faulty.
Possible Cause of Transmission Problem
Faulty electronic sensor or low/high automatic transmission fluid level.
How to Fix A/T Up shifts Problem
If the problem cause is the level of automatic transmission, it can be fixed by adding or draining the fluid to make the level within the normal range, if the fluid level is low, there might be a leak somewhere on the system, in this case bring the car to a reputable auto repair shop and ask the mechanic to check for the leak on the system.
If the problem is involving a faulty sensor, there is no other option but to bring the car to a repair shop specialized in automatic transmission and asks the mechanic to do some testing on the transmission to determine the exact cause of the problem.