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What Do These Meters Mean?

In addition to the lights on your dashboard that illuminate signaling that something needs checking, car dashboard meters are constantly communicating the most important things a driver needs to know while on the road. While many drivers would consider the two most important gauges on the vehicle the speedometer and fuel gauge, each vehicle is equipped with other gauges that provide useful information on the vehicle’s condition while on the road.

Most vehicle car dashboard gauges include the speedometer, fuel gauge, tachometer, water temperature gauge, and the oil pressure gauge. Here’s what you need to know about the dashboard meters and gauges and how each one may affect how you drive:

  • different car metersSpeedometer – The speedometer is a gauge that indicates the current speed the vehicle is traveling. Speedometers can be digital, like a digital clock, clearly indicating the speed, or mechanical using a needle to indicate the speed of the vehicle. Speedometers reflect the speed of the vehicle from the transmission output shaft speed sensor, which is then converted by the vehicle’s computer via an algorithm to display the proper speed. The old days the vehicles used a speedometer cable instead of a sensor. Pro Tip: Drivers should always monitor their speed for safety purposes and to avoid speeding tickets.
  • Fuel Gauge – The gauge notifies the driver how much fuel is left in the vehicle to burn for combustion. Without fuel, the engine cannot produce the power it needs to propel the vehicle. The gauge is connected to a component within the tank, attached to an arm or rail referred to as a “float” literally floats in the gas tank.  Most fuel gauges display the amount of fuel in a stick or digital bar as opposed to gallons remaining. The needle does not move constantly while the vehicle is moving because the gauge is using a system that averages out the reading in live time, similar to a percentage. Many vehicles are equipped with a digital low fuel indicator, advising drivers to stop and fill up the tank. However, relying on this indicator can prove detrimental for the fuel pump. Gas keeps the fuel pump from overheating and wearing out prematurely. Pro Tip: For a more accurate estimate of how much fuel is left in the tank, drivers should check the gauge when the vehicle is on a level surface and not accelerating or decelerating, It is recommended to fill the tank once it reaches ¼ tank to keep the fuel pump properly lubricated. Not sure where your gas cap is? In many newer cars, a small triangle, located right next to the fuel gauge, will point to the left or right side of the vehicle to indicate whether the gas cap can be found on the driver or passenger side.
  • Tachometer – The tachometer’s job is to display the speed of the engine in revolutions per minute or RPMs. Because transmissions have many gears, the speed of the car does not match engine speed and transmission gears are designed to convert the speed of the engine into acceleration and performance. A tachometer is helpful while pulling a trailer or going up and down steep grades. However, they’re most often used with manual transmissions to indicate to the driver when to shift gears. This function is of no use for drivers of automatic transmissions, as the vehicle will shift gears as needed.
  • Water Temperature Gauge – This gauge communicates the temperature of the vehicle’s engine coolant. A thermistor, attached to the engine block or thermostat housing, provides the information that is then displayed on your dashboard. While many vehicle dashboard gauges are analog or use needles to display the approximate temperature, some cars are able to provide a live, digital display of the temperature. The average temperature of a vehicle’s engine, while running, is about 195 – 220 degrees Fahrenheit. Many newer vehicles temperature reading are done by the vehicle’s computer and often triggers a warning light to illuminate if trouble is detected. Pro Tip: Pay close attention to your vehicle’s temperature gauge. An overheating engine can cause serious and permanent damage to the engine which could result in costly repairs or result in complete replacement.
  • Oil Pressure Gauge – Contrary to popular belief, the oil pressure gauge does not monitor the level of oil in the engine but instead the pressure of the oil being pushed through the engine. Similar to how blood pressure is monitored, the oil pressure gauge monitors the force pushing the oil through the engine using a sensor. A normal oil pressure, while the vehicle is in motion on the road, should be between 20 to 50 PSI (pounds per square inch) and can be significantly less when the vehicle is at an idle state. Pro Tip: Oil pressure will vary and can change based on the engine’s RPMs. If the oil pressure gauge drops or doesn’t read any pressure, turn the vehicle off immediately.