I had this transmission malfunction on my 2011 Fiesta (won't up-shift correctly) after replacing the battery last winter and finally had the car serviced the other day by my local private repair shop. I tried various tricks to get the controller to reprogram including disconnecting the battery again for a while and reconnecting, putting miles on the car, driving it through a series of acceleration runs at graduated intensity so it would "re-learn" proper shifting and nothing worked. I did find that the car can be forced to up-shift by putting the shift lever in neutral for a few seconds and waiting for the revs to drop, then back to drive. Still, it was a pain to have to do that every time I slowed enough to drop to a low gear. My service tech read the codes and cleared them, then told me I'd have to go to Ford for help. Anyway, the morning after he returned my car to my driveway I went out and started up and lo and behold, not only were the annoying error messages gone (which I expected since he cleared the codes) but the car drove and shifted normally again. Whether this will last once I've gone the required miles for the computer to register new faults again, I don't know.
If I were the suspicious type, I'd wonder if Ford did this on purpose to get people to see a dealer even though all they really need to do is clear the codes and the problem will disappear. If all else fails, get somebody at the local auto parts store to loan you a code reader and clear any codes. It just might be all you need.
Interesting....I took my daughter's 2011 Fiesta (150K) miles - when she bought a new car - to maintain it until my youngest granddaughter gets her license later this year. I want to give her a reasonably sound vehicle. In spite of high miles, the car is in good condition. Used vehicles are much more expensive than the usual upkeep to maintain this one- I told myself....
During the recent MLK holiday weekend, it wouldn't start in subzero weather so I jumpstarted it. It had been sluggish for the past few starts so I figured a new battery was needed and had my local auto supply store replace it with a premium battery. On the way over, I found it would not shift beyond 3rd and getting to that required 3500RPM. Long story short, I figured cold had gummed up the tranny somehow never giving a dead battery a thought. I went to AAMCO later for advice. He spent a week (COVID caused employee shortages) diagnosing the problem but neither his nor a Ford employee friend's diagnosing system could get the TCM response expected other than an indication it was mechanically OK, I retrieved it 2 days ago. I am back with the auto shifting really wonky. The guy said he did get it to go through all 6 gears but at VERY high RPM, as I had experienced.
Yesterday, I took it to Ford for some overdue recalls my daughter had avoided, but unfortunately, those related to TCM had expired. I was floored at the cost of them diagnosing the transmission issues further so I have been doing web searches and reading the owners guide (which I should have done before touching the battery issue). Anyway, on page 298 of my user guide there are cautionary steps related to transmission relearning after battery replacement. A TCM replacement is not available anywhere in NH for several months and is downright expensive. Perhaps wishful thinking, but it did seem that the transmission was SLOWLY learning because it seemed to shift up and down just tiny bit better the last time I drove it (yesterday).The AAMCO guy told me that driving it won't hurt if done sensibly.
We are again in the throes of near blizzard conditions here so I won't be driving for at least a day. However, the steps described in the manual (some posters have tried some of these) are free so I am going to give those a try as soon as the weather allows. Will post an update afterward.