Car Gauges And What They Mean
There are six most important car gauges: the speedometer, fuel gauge, tachometer, temperature gauge, odometer, and voltmeter. Here’s how to read them.
Written by Patrick Price
Reviewed by Jessica Barrett
Table of Contents
- What are the different dashboard gauges?
- How do car gauges work?
- What to do when your car gauges or dashboard lights aren’t working
- Find hassle-free car insurance
- FAQs
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On your car’s dashboard, there are several gauges—either digital or analog, depending on the model and year of your vehicle. These gauges serve as diagnostic tools to provide the driver with real-time data regarding speed, fuel level, engine temperature, RPMs, battery charge, and more.
The gauges on a car’s dashboard are among the most important tools a driver has for monitoring the vehicle’s vital systems. These gauges are grouped together in a section of the dash just above the steering wheel—which is called the gauge cluster or instrument cluster.
The information displayed by these gauges is as crucial as it is easy to understand, but if you’re unfamiliar with the six major gauges, they can seem a bit confusing.
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Find insurance savingsWhat are the different dashboard gauges?
There are six types of gauges in virtually every car: the speedometer, fuel gauge, tachometer, odometer, temperature gauge, and voltmeter.
Those are just the six most common gauges found in modern cars. You may have a few additional gauges—such as an oil pressure gauge (which indicates the current engine oil pressure) or an oil temperature gauge (which indicates your oil’s temperature)—but these are less common today.
Instead, most newer vehicles simply have a warning light to alert you if the oil level and/or temperature are outside of the normal range.
Speedometer
The most fundamental gauge in your car is its speedometer, which tells you exactly how fast you are going. This gauge will typically be larger than the others and labeled with numbers ranging from 0 up to around 160 or 190 (depending on your car). These numbers represent how many miles per hour (MPH) you are traveling.
In older cars, the speedometer gauged your speed indirectly via a connection to the car’s transmission. In modern vehicles, the speed is measured by an electronic sensor that reads the speed of your tires by counting the number of rotations they make per second.
Pro Tip The speedometer is specifically calibrated for your vehicle’s stock tire size. If you install aftermarket tires of a different size or if your tire pressure is too low, you’ll receive inaccurate speedometer readings.
Fuel gauge
Another of your car’s most important gauges is the fuel gauge. This is the indicator that displays the amount of fuel in your fuel tank.
The fuel gauge is usually located toward the far left side of the instrument cluster and is one of the smaller indicators. It can be identified by the nine lines representing an empty tank (indicated by the letter E), ⅛ of a tank, ¼ of a tank, ½ tank, ⅝ of a tank, ¾ of a tank, ⅞ of a tank, and a full tank of gas (indicated by the letter F).
In general, it’s not a good idea to drive for any extended period of time with less than ¼ of a tank of gas. Doing so could leave you stranded in the middle of the road or cause serious damage to your fuel pump!
Tachometer
Next up, we have the tachometer. This gauge is traditionally situated to the left of the speedometerand will have numbers ranging from 0 to 6, 7, or 8—though some go as high as 9 or 10. These numbers represent your engine speed in revolutions per minute (RPM).
These numbers aren’t your actual engine speed, though. You’ll need to multiply them by 1,000 in order to get the exact number of revolutions. For example, if the needle of your tachometer is pointing at 6, that means your current engine speed is 6,000 RPM.
Some tachometers have their numbers written in intervals of 10 rather than intervals of 1. For these tachometers, you’ll multiply the reading by 100 instead of 1,000.
At the higher end of the tachometer, you’ll notice that there is a red section. This indicates the “danger zone”—meaning the RPM range that’s unsafe for your particular engine. Every engine has a different speed tolerance. Some can operate at 6,000 or even 7,000 RPM without a problem. Others will be in danger of serious engine damage if they run anything higher than 5,000 RPM.
The tachometer is an important gauge. It helps monitor engine strain and optimize fuel economy. That being said, it mostly only matters if your car has a manual transmission. Automatic transmissions are designed to read and react to the engine’s speed all on their own.
Temperature gauge
As the name suggests, temperature gauges read and report your engine’s temperature. At one end of the temp gauge, you’ll see the letter C, which stands for cold. On the opposite end, you’ll see the letter H, which stands for hot.
If your engine temperature gets too high, it could begin
overheating
, which can quickly cause catastrophic engine damage. Normally, the temperature is kept in check by the radiator and the engine coolant fluid. The gauge reads the temperature of the coolant fluid in order to determine the engine’s overall temperature. If the coolant temperature is too high, that means the engine is in danger of overheating.
Odometer
The odometeris one of the simplest gauges to understand. It displays the number of miles your car has traveled—both during your current trip (since the last time you reset the odometer) and throughout the vehicle’s entire lifespan.
Voltmeter
Finally, we have the voltmeter. This gauge is part of the 12-voltelectrical system that works to keep your battery charged.
When your car starts, it uses electricity from the battery to initiate combustion. Once the engine is running, though, all the power that’s needed to operate the vehicle’s electrical systems (radio, headlights, turn signals, etc.) comes from the alternator.
The alternator converts some of the mechanical energy from your combustion engine into electrical energy. It then uses that electricity to power various electrical systems—including the charging system that recharges your car battery.
As long as the alternator is doing its job, your voltmeter should read 12-13 volts when the car is off and 14-15 volts when it’s running. If you see readings outside of that range, you should have your vehicle looked over by a mechanic.
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How do car gauges work?
Each type of car gauge works a little bit differently. They can be either digital or analogand typically use various electrical sensors to monitor how well your car is running. These readings are then displayed on the dashboard indicators for the driver to see.
Precisely what type of equipment a gauge uses to take readings—and just what those readings are measuring—depends entirely on the type of gauge. How a speedometerworks will be quite different than how a voltmeterworks.
You can find detailed descriptions of how each gauge type works in the corresponding sections above.
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What to do when your car gauges or dashboard lights aren’t working
If you notice that any of the gauges or warning lights in your instrument cluster aren’t working properly, you’ll need to resolve the situation immediately. Otherwise, you’ll have no way of knowing when there’s a problem with your vehicle, how much gas is left in your tank, or even how fast you’re driving!
Some cars have a built-in reset function for their gauge cluster. If your car has such a system, it’s certainly worth trying a reset. That can sometimes get things working properly again.
But most of the time, problems of this nature will require the help of a trained automotive electrician.
Find hassle-free car insurance
Keeping a close on your car’s gauges is a crucial part of proper vehicle operation and maintenance. Keeping a close eye on your car insurance policy is also an important part of keeping your car in good shape
Reviewing your policy at least once a year, and comparing it with quotes from other providers, is the only surefire way to avoid overpaying for your insurance.
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FAQs
What can you tell from the gauges on a car dash?
The gauges on your car dash provide all the critical information about your car’s current status and operating levels. This includes things like your current speed, total mileage, engine temperature, oil pressure, battery voltage, and more.
What are the three most important gauges in a car?
All of the gauges in your instrument cluster are important indicators of vehicle performance. That being said, however, it’s most urgent that you become familiar with the speedometer, fuel gauge, and temperature gauge. Without those, even the most basic vehicle operation will be problematic.
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