Is there a simple device out there that lets you see the water temperature that the ECU is picking up from the sensor. My temp gauge is acting funny and it spiking when the car is traveling fast. I want to see the reading from the ECU sensor (which is right next to the gauge sensor) to see if the fluctuation is actually happening. I’ve seen some handheld units on ebay and I’m assuming they plug in behind the ask tray. But some insight would be great to make sure I get something I can read the temp with.

Thanks!