Your car temperature gauge seems straightforward: a needle that shows you whether your engine is hot or cold, with a “safe zone” of temperatures in between. However, not every car has this type of setup, as some feature a digital readout with actual temperature numbers, and others simply have a red light for “hot” and a blue light for “cold.”
Reading and understanding your car temperature gauge doesn’t have to be a complete mystery. Plus, an overheated motor can lead to expensive repairs, so it’s fairly important to know how to react to the information your vehicle is giving you.
Different Gauges, Different Data
The vast majority of car temperature gauge systems feature a numberless panel with a needle that swings from C to H. It’s a mistake, however, to think that this type of gauge is giving you an accurate readout of your car’s motor temp. In fact, that middle section of the gauge, between the cold and the hot readings, can represent a wide range of temperatures that the car’s computer interprets as “normal.” Unless there’s a significant swing in temperature in your engine, it’s unlikely the needle will move from that spot.
Other vehicles can provide a more direct readout of actual temperatures that, in some cases, requires you to know what’s too hot and what’s too cold. A digital gauge that shows you the degrees Fahrenheit inside your motor is useful if you’re a gearhead, but if you’re just trying to get to work you should keep in mind that anything over 240 degrees is starting to get worrisome.
If things get out of hand, then even a digital gauge will sound an alarm, either by blinking or chiming to get your attention that the engine temperature is rising too high. Cars that don’t have a gauge at all will do the same thing, illuminating a light on your dash that indicates your engine is now in the danger zone.
Too Cold? Don’t Worry
With a modern engine, you don’t have to worry about running too cold. Although some high performance vehicles might restrict how high you can rev the motor until they’ve warmed up a bit, even in the dead of winter there’s no need to let a car sit idling until the temperature gauge swings into the middle. Your vehicle’s computer will compensate with the right amount of fuel and air no matter how cold it is outside.
Too Hot? Shut It Down
An engine that’s running too hot, as indicated by the gauge needle hitting H, the chiming of an alarm, a flashing red light or steam rising from under your hood, is another story. If you find yourself dealing with one of these warnings, you should pull off the road and shut the car down as soon as possible. Don’t open the hood to avoid getting burned by steam or superheated engine coolant, but keep accessory power on so you can watch the gauge and see if the temperature drops back down into the safety zone. If not, then you should call roadside assistance to tow your vehicle to the garage so as not to risk any further damage.
Check out all the relays, sensors and switches
Photo courtesy of Freeimages
Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.