2004 Jeep Liberty Transmission P0075 “HIGH TEMPERATURE OPERATION ACTIVATED”

I recently purchase about two months ago a 2004 Keep Liberty with the 3.7L, 42RLE transmission and 111,150 miles on it now. I was told there was a used transmission installed, but wasn’t provided the millage of the used transmission. I could tell there was brand new fluid in the transmission and the pan looked like it was recently off and new sealant applied.

The issue I have noticed is after driving on a hot day (75-95 degrees outside temp) and after a lot of hill climbing the transmission seems to struggle a little coming out of 3rd gear and into 4th on a strait away. I have to feather on and off the accelerator a bit to make it shift into 4th. I am not very familiar with Chrysler transmissions and how they are supposed to shift or feel. I have noticed the 3rd to 4th doesn’t feel as productive as the other shift in all temperatures, but really acts up when hot.

At least 3 times I have gotten a Transmission Code P0075 “HIGH TEMPERATURE OPERATION ACTIVATED” in the transmission computer. I cleared the code and after running on a hot day with hill climbing it returns. I have never gotten a check engine light or Trans Temp light (the light does come on when first turning key to on position). Being I have a nice Autel Scanner, I ran the Live Data and went for a drive. The transmission fluid temperature ranges from 213 degrees to 234 degrees when driving once reaching engine operating temp. When on a strait away or when coasting down a hill it reads the lower temp, but when climbing a hill it reaches as high as 228-234 degrees. It does have an external cooler in this year that is located in front of the radiator. I also wanted to mention the trans fluid temp sensor reads -2 degrees when engine is off. It jumps between the temperatures and doesn’t change temp reading gradually. One minute its 213 degrees then next its up to 222 degrees. Could it be I just have a bad transmission fluid temp sensor?