Prius Prime External Temperature Display/Gauge Inaccurate

I have a 2017 also and I don't have that problem. Mine seems to be very close to local weather from a few different sources.

 

I don't have a problem with it, but I have seen the gauge be off by 5 to 10 degrees from what the weather app on the MID shows and also the temp gauge in my older hybrid. I noticed it in the winter during sub freezing temps. I've also noticed that the gauge will usually get closer to the actual temp as I'm driving, especially on longer trips (more than 10 miles or so to pick a semi random number). It usually gets real close to actual or right on (well right on, as far as I know what the actual temp outside really is).

 

I tend to suspect that the "official" temperature isn't taken with a sensor placed a foot or two above hot asphalt. Mine reads crazy high as I start out, but comes down closer to actual after a few miles.

 

Mine will lag the outdoor temperature for a long period of time. Park car in garage at 82F, when outside temp is 98F. Drive the car in EV 4 miles out, park, 4 miles back, reading maybe 85F. I haven't experimented, but it appears that when the grill louvers are closed or ICE is not running, there isn't much airflow over the temperature sensor.

 

I think mine reads high. I'm not sure where the sensor is, but maybe because of its location it's not reading true ambient temperature.

 

The sensor can be adjusted + or - 2 or 3 degrees using an OBD reader such as Carista, or by the dealer for a small (HA!) fee. However, I haven't seen any real reason to adjust mine.

 

Parked in the sun on the asphalt parking lot all day, it always reads higher than the official local temperature which is read in a shade 3-4 feet above the ground. As soon as I start driving away, it seems to adjust. Parked overnight, the temperature is always very close to what the ambient temperature outside of the car or inside of the cabin.

 

See this previous thread: Outside temperature reading incorrect. | PriusChat