Excessive heat can kill automatic transmissions. One of the ways to combat rising temperatures is to add a transmission cooler and installing a transmission temperature gauge to monitor just how hot your transmission is getting, while off-roading. Where do you put the sensor? You will only need one gauge. Some people like to run 2 gauges (before and after the cooler). The best place for the gauge sensor is in the transmission pan since that is the fluid that the transmission is drawing from. Many aftermarket pans offer locations for temperature sensors as well as offering more fluid capacity. Otherwise, we recommend installing it in the line before the fluid returns to the transmission. How hot is too hot for your transmission? Normally you will see a 50-degree drop with a transmission cooler. If you see over 200 degrees on your gauge, you don’t need to panic or immediately pull over and stop. Just bear in mind that the longer it runs over 200 degrees (or 176 degrees for an AW4), the, shorter the life of the fluid will be. There is a direct correlation between how hot the transmission gets and how long it is expected to last. Even synthetic fluids are subject to this kind of accelerated wear, and while the mileage values might bump up, all fluids will break down if you get them hot enough-so keep it cool.