What Are the Gauges in a Car? [Car Gauges Explained]

If you are a first-time driver, you might not know what the gauges are in a car. For the uninitiated, the gauge cluster might seem confusing, but you must know what they do. So what are the gauges in a car?

The minimum number of gauges that a passenger car’s dashboard can have is two – the speedometer and the fuel gauge. The additional gauges that you may see are the engine temperature gauge, tachometer, voltmeter, and oil pressure gauge.

Read on to learn more about these gauges and how to interpret and use the information that they provide.

What Are the Gauges in a Car?

What Are the Gauges in a Car

Through the eyes of a newbie driver, the gauges in a car’s dashboard can seem confusing. However, they are not as difficult to understand at all. You will also discover that knowing what each gauge is showing will make your driving experience a whole lot easier.

Here are the most common gauges that you will see in most cars and how to read them. You will also learn some of the reasons why these gauges might give the wrong reading and how to fix them:

1. Speedometer

Gauges the Speed of the Vehicle

This is the most important of all the gauges in your dashboard, which is why it is also the biggest. In the past, speedometers used a flexible cable that spins inside a flexible tubular housing. This is to gauge the speed of the vehicle. One end of the cable connects to the speedometer while the other end is hooked on the transmission.

Modern cars have ditched this analog method of measuring speed with an electronic sensor that measures the wheels’ speed. They will then send the information to an electronic speedometer.

Tire’s Size Affects Speedometer

Certain factors can affect the accuracy of your car’s speedometer. One of them is the size of your tires. If you decide to swap out the tires for a bigger set, you must recalibrate your speedometer. Since the speedometer monitors the RPMs of your wheels, putting on bigger wheels in your car will give false readings. Bigger wheels spin slower than smaller ones.

Incorrect Speedometer Gear within the Transmission

Another reason for wrong speedometer readings, primarily on older cars, is an incorrect speedometer gear within the transmission. However, this issue is relatively rare since it will only happen if you change your car’s transmission. In addition, professional mechanics know that they need to use the proper speedometer gear when they swap transmissions.

On modern vehicles, speedometer calibration is much easier. However, it is still advisable to have a professional do it. If you replaced your car’s wheels with bigger ones, swing by a tire shop so they will electronically calibrate your speedometer.

2. Fuel Gauge

Measures the Amount of Fuel Left in the Tank

Compared to the other gauges in the dashboard, the fuel gauge is the most inaccurate. Surprisingly, car manufacturers designed it to be that way. In older cars, the fuel gauges are analog. A cable connects them to a float gauge that is in the fuel tank. Nowadays, fuel gauges are digital. They use electronic sensors to measure the amount of fuel left in the tank.

Damaged or Loose Float in Older Tanks

One issue could be damaged or loose float in older tanks. A sign is when your fuel gauge does not seem to move past empty. This can be a difficult issue to fix since it will require the removal of the entire fuel tank.

Inaccurate Fuel Gauge

There are also not-so-serious issues, per se, but are more like deliberate designs. For instance, when you fill up your tank, the fuel gauge needle stays full for a couple of miles. It will then drop slowly up until the ¾ level.

After that, the gauge will start going down much faster. This is a psychological trick to give new car owners the impression that their cars are getting good gas mileage. However, not all fuel gauges are like this. Some are more accurate than others, but not by much.

Also, even when the fuel gauge drops below the E (empty), and the fuel tank light turns on, that does not mean your car will immediately stall due to lack of fuel. There’s still usually a gallon or two left in the tank as a reserve. This means you can still make it to the nearest gas station.

Not Advisable to Let the Fuel Gauge Drop Below the 1/4 Mark

However, it is not advisable to let the fuel gauge drop below the ¼ mark. If the fuel level is this low, it exposes the fuel pump. If the fuel pump is not submerged in the fuel, it tends to heat up considerably. This can cause a significant amount of wear and tear. Do this many times, and your fuel pump will eventually fail. The problem is that it is expensive to replace.

3. Warning Lamp or Temperature Gauge

what are the gauges in a car called

Measures the Engine Coolant’s Temperature

The temperature gauge measures the temperature of the engine coolant. When you first start your car’s engine, the temperature gauge will read cold. However, after a couple of minutes, the needle will steadily rise.

Most temperature gauges, however, do not indicate the number of degrees. You will usually get a simplified version that reads hot or cold. The gauge will also end up being divided into blue (cold), white (normal), and red (hot) zones.

Temperature Warning Light Instead of Temperature Gauge

However, not all cars come with temperature gauges. Instead, they will have a temperature warning light. If you see a symbol in the shape of a thermometer light up in your dash, your engine is overheating. In that case, you need to pull over immediately.

Stop Driving If Your Car Is Overheating

Speaking of overheating, you should not continue driving if your engine is overheating. Pull your car over to the side of the road. Open the hood and let the engine cool down. You will be risking permanent engine damage if you continue driving.

Also, never take the cap off the radiator while the engine is hot. It is a good way to get 3rd-degree burns from the boiling coolant.

Again, what are the gauges in a car? Speedometer and Fuel gauge are the most common gauges in a car. Other gauges include the temperature gauge, tachometer, oil pressure gauge, and voltmeter.

4. Tachometer

Measures the Rate at Which the Engine Is Turning

The tachometer measures the rate at which the engine is turning. It displays it in revolutions per minute (RPM). Usually, you will find single-digits displayed on the tach, with a little “x 1000” in the middle. This means you need to multiply the number on the tach by 1000. If the needle is between two and three, that means your engine is turning at 2,500 RPM.

Useful If You’re Driving a Manual Transmission

If you’re driving a regular automatic transmission without paddle shifters or manual mode, your dash will not likely have a tachometer. The tachometer is quite useful if you drive a manual transmission (stick shift). The reason is that it will tell you when it is the optimal time to shift into gear. This will help you get the best fuel economy or the best acceleration.

Warning If You’re Pushing Your Engine Too Hard

The tachometer also serves as a warning if you are pushing your engine too hard. Never let the needle get into the red zone. The reason is that doing so will only cause serious engine damage in the long run.

5. Oil Pressure Gauge or Warning Lamp

Measures the Engine’s Oil Pressure

This gauge measures the engine’s oil pressure. You can see it being displayed in pounds per square inch (psi). This tells you if your car is running low on oil. Either your engine has a serious leak, or your oil is so dirty that it is hard to flow.

Present in Older Model Cars and Utility Vehicles

You will usually find this gauge in older model cars and some utility vehicles. However, if you’re driving a rather newer model, you might not have an oil pressure gauge. You will indeed have a low oil warning light flashing if you are low on oil.

Pull Over When the Gauge Drops to a Low Level

If the gauge suddenly drops to a dangerously low level, carefully pull over to the side of the road. Do the same if your low-oil warning light starts flashing. Check the oil level using the dipstick, and top off the oil if needed. Driving with dangerously low oil pressure, even for just a mile or two, can cause serious damage to the engine.

6. Voltmeter

what are the three most important gauges in a car

Shows the Car’s Battery Health

The voltmeter is the gauge that shows the battery health of the car. Most passenger cars do not have this gauge. However, it will typically have a battery-low warning light. If this suddenly turns on, it means there is something wrong with your car’s electrical system.

Modern Automobiles Have a 12-volt Electrical Systems

Modern automobiles come with 12-volt electrical systems. This means a fully charged and functioning car battery should read about 12.5 volts when the engine is not running. If the engine is running, the charging system (the alternator) will be recharging the battery.

The voltmeter should be showing around 14.5 volts. Unless a heavy load like wipers, lights, heater, and other features come on, causing a voltage drop.

If Voltmeter Drops, You Will Not Be Able to Start the Car

Unlike the fuel or oil pressure, if the voltmeter drops, it will usually not cause serious damage to your car. However, you will not be able to start the car unless you get a jumpstart from another car.

These are the most common gauges that you will find in the average passenger car. Do not be surprised if you do not see most of these gauges in your car. You will still have enough warning systems to inform you if there is anything wrong with your car.

What to Do When Your Gauges or Dashboard Lights Are Not Working

Regardless if you are dealing with dashboard gauges or lights, the basic troubleshooting process involves narrowing down the symptoms. Detect the signs and symptoms until you reach the main problem:

All the Gauges and Warning Lights Stop Working

If that happens, the problem is something that the gauges and lights share:

  • Check the fuses. Find your vehicle’s fuse box and locate the fuse for the instrument cluster. It typically has the label “gauges”, “cluster”, or anything similar. In case of a busted fuse, replace it and check it got fixed after that;
  • Check if the instrument panel is getting power. Check for a grounded connection in case the instrument cluster indeed has power; and
  • If nothing seems to fix the problem, you may need to replace the entire instrument cluster.

When Only One Gauge or Light Is Not Working

Diagnosing just a single bad gauge or light means you need to locate the sensor it connects to. Disconnect the sensor. Depending on how the instrument works, you will need to connect the sensor to the ground. This will help you figure out if it still works. On the other hand, the sensor connection might be loose, and you only need to reconnect it.

Conclusion – What Are the Gauges in a Car?

All passenger cars have a minimum of two gauges in their dashboards. These are the speedometer and fuel gauge. Additional gauges that you might see in other cars include the engine temperature gauge, tachometer, voltmeter, and oil pressure gauge.

If you are a new driver, it will be in your best interest to familiarize yourself with these gauges. Also, study the potential issues that these gauges can tell you. This knowledge will come in handy in the future. It may even help save your car from massive damage.

Related reading:

How Long Can You Drive with Check Engine Light On?

Check Engine Light On and Off Intermittently [Causes and Fixes]

“Check Gauge” Light – What Does It Mean?

Acura VSA Light – What Is It?