I'm the second owner. Since my mazda3 (2006 auto 2.3L) is for commuting, I normally drive via highway for about 15miles.
Since always I drive it early morning & evening, I don't need to use A/C... until now...

Today I drove my mazda3 to downtown, with many traffic light, also with A/C (Hot Texan Weather!)

While in downtown, it started to shift very roughly from 2 to 3 or 3 to 4. Also, did not shift down from 4 in slow speed.

After a while, suddenly... (just before I was going up to hiway.)

1) AT light on
2) tranny locked to '2' when it stopped.
3) manual mode doesn't work. (I used manual mode a little, due to rough shift.)

In the manual, it says 'If the automatic transaxle fluid (ATF) temperature becomes too high, there is the possibility that the transaxle will switch to automatic shift mode, canceling manual shift mode and turning off the gear position indicator illumination. This is a normal function to protect the AT.'. Might it be a just this issue?

After a while, (turning off the key and wait some minutes.) it came back to normal.

Do you think that it is a simply (?) overheat issue?

Maybe mechanics or dealers say ATF flush or similar. Can it solve the problem?

 

definitely sounds like an overheat issue - make sure your fluid levels are ok. and did the engine temp look steady when this happened?

 

Hello,
I have the same problem with mazda 3 (2011)
If I drive it high turnover of motor (not speed) I gives same problem.
First the numbers fade away in manual mode and you can not switch it, then AT lamp turns on.
I met this problem after change the ATF. I was driving in high way with high speed the AT Lamp had turned on. I pulled over and check it, every where around the oil dipstick had covered with oil. I though I need to add ATF and I did it. First it is solved but then same again.
(I need to say, before change the oil, I never force or test it high turnover.)
I gave the car to Mazda. The oil is burned you need change it and filter aswell. I changed. But did not work. Same problem. It continue.
Right now I have focus heater radiator. Bcos time to time the coolant is running out. Mazda has already control it as well. However, according to them there is no reason for it. They could not fnd anything about it. One of my friend he ask me whether some water get inside the car to the passenger seat or not.
I said yes.
He asked again, the aircon works properly or not?
Yes you right, it gives problem as well especially the weather is too hot.
He said, Ok you need to check your heater radiator. Most probably, inside of it there is some stuck and the coolant can not circulate and also has a leak and the coolant water running out over there.
Indeed when I check the heater radiator, there are some dust at the joint point. I am not an expert but it looks that the reason of AT problem is, bad circulation of coolant.
At my last trip, when the sun at peak, it give same problem at 33-40C degree also aircon was gone. But around evening when the temp decreases to 28C degree, it did not. Maybe It was just a luck or I drive easy.
I am going to change the heater radiator and I will kindly let you know about the result.
If you share how fix it, I will be happy
Thanks in advance
Sincerly