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Why Cars Give Inaccurate Outside Temperature Readings

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Photo: Pixabay

If your vehicle has a dashboard temperature display, you’ve probably noticed at least a few instances when it seemed to give the wrong temperature. You’re not alone. Apparently, this is a common issue with many vehicles’ outside temperature displays, especially in extremely hot or cold weather. And it has a lot to do with the type of thermometer the car uses and where it is placed.

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Photo: Pixabay

Thermometers vs. thermistors

According to The Washington Post, most autos use thermistors instead of thermometers. While thermometers rely on a liquid like mercury to measure temperature, thermistors rely on reading the change in electrical current of the heat that is added or taken away.

The pros and cons of thermistors

A few of the strengths thermistors have is that they are economical, small, and convenient to use. Their main weakness comes in the form of inaccurate temperature readings. Interestingly enough, thermistors are mostly accurate, as The Post confirms. However, they do give inaccurate readings from time to time because of where they are placed on the vehicle.

Automakers usually place behind the front bumper of the vehicle. So on a hot summer day, for example, a car’s thermistor is vulnerable to absorbing reradiated heat from the road surface. This, in turn, can trigger a higher temperature reading than what your weather-forecasting app displays.

And, per Dallas News, thermistors tend to give more accurate readings at night, when there’s less heat reradiating off of the asphalt. They also tend to be more accurate when the car is in-motion on the highway rather than stuck in a traffic jam since the artificial heating effect is minimized.

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News Sources: Dallas News, The Washington Post