I hope someone out there can help me! I have a 2010 Mazda 3s that I purchased a year ago from Carvana. It only had 52k miles on it. Shortly after purchasing I found out why the previous owner probably got rid of it. Frequently the automatic transmission sticks in 3rd and occasionally 4th gear. The only way I have found to make it switch is to push the shifter over to sport mode and back to drive mode. As soon as I do it continues to proceed to 5th gear. I had a warranty when I first bought the car, so I took it to aamco which was one of the approved facilities. They had it for 5 out of the first 9 weeks that I owned it. They replace the transmission control module and also the throttle body but neither one fix the problem. I even took it to the Mazda dealer and they told me they couldn't find anything wrong with it. Although I think they just didn't want to mess with it. I'm not getting any error codes. Surely to God I'm not the only one that's ever had this problem.

 

Well reading your information a couple things...
1) Not all AAMCO have a complete staff that are actually up to date on the newest transmission designs. If they say they are then they would have the Technician that is working on your MAZDA having a current certification .

Dealership also do not always have experts in specific troubles like transmissions. Again this goes back to who the service employee was that was working on your Mazda. If you paid for the service and it did not correct the problem I would inquire was it a Mazda employee worked on the diagnosis? If Trained and Mazda current certified Mazda Technician or current ASE? The problem should have been found before parts were what I think random guesses to the problem.

I would be asking about the Mada record service history and hopefully some record of basic transmission service? MY guess neither because of your stated miles. BTW this is NOT a common problem and if you do find someone reporting other wise read all the details about there issue !

Unfortunately your Mazda is out of powertrain WARRATY so you need to go to a better shop.

My advise is to check and find a Transmision specify shop that has been in business for at least a couple or more decades and a good BBB report. Talk to them about your problem and what was already done. If you posted all that was done to your Mazda to find the problem that your next shop will like me, see that there were several steps that were not done to diagnosis your problem's.
Don't get discourage if at this point they do not want to look at your Mazda because of the already misdiagnosed service that was done already. In which case you may need to do more Transmision shop service shop seeking.
I can tell you honestly if you were to come to our shop even though I am very experienced in automatic transmissions would call my friend that all his shop does is Transmission service, referring the work to him after I got the ok to send you to him.

Advise for the future and any other member reading this... NEVER NEVER NEVER agree to pay for parts or service that did not correct your problem. Sign only the work order for diagnosis not for the repair which they should get a confirmation if not a anther signature authorizing the work.