It is better to keep the sensor in its original location i.e. behind the engine block. Placing it near the T-valve will somehow measure the wrong temperature. Just think of it like this:
When you cold start your car with your sensor located near T-state valve, the coolant will start flowing inside engine, will warm it up and will not fully come out of the T-valve unless engine reaches its optimum temperature. Now you have cold radiator pipe in the vicinity of T-valve and engine is warming up. The temperature needle inside instrumental cluster will stick to cold point. Why?? Because the sensor is located outside the warm engine block. During the warm-up process, the quantity of cool coolant in the radiator pipe is albeit higher than that of incoming hot coolant whereas engine is full of hot coolant. This difference in temperature will cause error in reading if sensor is not located at its proper place. So in this case, it is better to place temp sensor to its original location. The company engineers have put it there for some reason.
Why don't check the temperature with some instrument like infrared thermometer? put thermometer at engine block and then near T-valve to check and see.
I may be wrong. But this is what is my opinion.
