Cars are a vocal lot. Most of the time they just rev away happily, but sometimes the noises can be a bit more sinister, which brings on the question: just what do those noises mean? Petroleum fuels are made from hydrocarbons : the molecules inside consist mostly of carbon and hydrogen atoms (with a fewer other elements, such as oxygen, attached for good measure). Wood, paper, and coal also contain hydrocarbons. We can turn hydrocarbons into useful energy simply by burning them. When you burn hydrocarbons in air, their molecules split apart. The carbon and hydrogen combine with oxygen from the air to make carbon dioxide gas and water, while the energy that held the molecules together is released as heat. This process, which is called combustion , releases huge amounts of energy. When you sit round a camp fire, warming yourself near the flames, you're really soaking up energy produced by billions of molecules cracking open and splitting apart! More information https://telegra.ph/Keeping-Your-Ride-Smooth-The-Importance-and-Cost-of-Tire-Balancing-05-31 Suggested by Aris Mone. Immediately turn off the air conditioner to reduce stress on the engine. Then, turn the dial to maximum heat. This can help pull heat away from the engine to keep it from overheating until you can pull over in a safe location. You may get a little hot yourself, but a few minutes of discomfort is a small price to pay compared to major engine repairs. Semiconductor sensors are by far the most common type and consist of a semiconductor resistor element in a metal capsule. The resistance of the semiconductor decreases as the temperature increases. As the engine heats up, the sensor resistance reduces, increasing the current flow to the gauge and giving a higher reading. More in How it works. 6. Malfunctioning Computer.