Could be my sensor but mine reads 9-10 degrees cooler than what the Toyobd1 sees. I'm happy with that (even though it maybe false).The main reason I was using mine was to watch Eng temps in real time.
Then I just ended up adding a temp gauge as it won’t melt down.
If you add the sensor to the upper radiator hose you’ll be reading the coolant at its hottest point coming right out of the head
And the reading will be hotter the then the OBD1 reading because it’s getting its information from the factory sensor and a different spot.
Tapped a sensor in the output of the engine (top hose). I have Trail tech.