Review on 🚗 ESUPPORT Car 2" 52mm Digital Oil Temperature Gauge with Blue LED Light - Automotive Temperature Meter by Ken Hamdan

Overall this is a good temperature sensor for the money. BUT - it MUST be properly grounded and the cryptic instructions say nothing about it. The ground for the power supply is different from the ground for the sensor. Only 12 volts for the hot power pin and almost any "good" ground for the negative power pin. If the sensor connected to your radiator's water supply is not grounded at all, it will read 104 degrees Fahrenheit. This is probably the lower limit of the sensor's ability to measure temperature. When you connect the ground wire from the chassis to the electrically isolated sensor wire, 302 degrees Fahrenheit will display and the red warning LED will illuminate. Probably 302 is the upper limit of the sensor range. But if you connect a good ground wire (e.g. straight from the battery) to the FITTING that the sensor is screwed into, the temperature will show correctly. I figured this would NOT work because I used teflon tape on various pipe adapters that I had to use to mount the sensor where I was measuring the water temp. I figured the teflon would insulate it electrically. But it works, I don't know why. I think the effective range of the sensor is 104 to 302 degrees Fahrenheit. So don't worry if you see 104 or 302 degrees. You just need to properly ground the temperature sensor.