Why your car thermometer is often wrong

Driving around Queensland in summer it’s hard not to believe your car’s thermometer when it tells you it’s 60 degrees outside. However, the likelihood you’re surviving Planet Mars-like temperatures is highly unlikely. So why is it that car thermometers don’t always seem to be right?

Just to clarify, car thermometers aren’t thermometers at all – they’re thermistors. Rather than measuring heat, they look at changes in electrical current after heat is added or removed. Thermometers and thermistors largely do the same thing. The main cause for inaccurate readings is due to the placement of the thermistor.

Most thermistors are placed at the front of the vehicle, behind the grille, which means they’re susceptible to measuring heat coming from the road as well as the outside air temperature. That’s why on a hot Queensland day, the temperature appears that much hotter.

The best way to get a reading is to observe it when the car is moving.

Use the car’s temperature gauge as a guide. A weather app is likely to give you a far more accurate reading – but remember, only check it once you’ve pulled over and the car is off.