Car Gauges: Types and How to Read Them

Every car, irrespective of its model and type, contains a minimum of two dashboard gauges, the speedometer and fuel gauge. Along with these, there are certain additional gauges in most cars. These include a temperature gauge, tachometer, voltmeter and oil pressure gauge.

If you want to learn more about these gauges, continue reading.

In simple words, gauges are those dials and sensors that help a driver to monitor various systems of a car. For every driver, it is essential to learn about these details before taking off on the road. Monitoring dash gauges while driving is crucial because it displays issues and malfunctions in a car.

Gauges are generally available on a car’s dashboard, hence this name. Depending on the manufacturing technologies, two variants of gauges are primarily seen in today's market, digital and analog gauges. It might seem a bit confusing at first, but once you know its features, it will be a cakewalk to understand them.

These are six common types of dashboard gauges. Let's understand their functions and how one can read them.

1. Speedometer

If someone has to rank the most important gauge in a car, it would be the speedometer. However, a speedometer’s function is highly dependent on car tyres. Therefore, even minor inaccuracies can affect your car’s speed. Previously a car’s speed was measured through a complicated system, but it got simplified with the electronic sensors.

How to Read a Speedometer?

Speedometers contain two semicircles with markings. The smaller or inner semicircle indicates your car's speed in kilometres per hour (km/h). However, the outer semicircle indicates your speed in miles per hour (mph).

2. Fuel Gauge

Another crucial dash instrument is the fuel gauge. Car manufacturers deliberately made it for inaccurate reading. After filling the tank, you will notice that this gauge stays on the full (F) sign for a long time and gradually drops. When this needle points at the empty sign (E), it still contains some fuel (1-2 gallons) in reserve.

How to Read a Fuel Gauge?

Reading a fuel gauge is the simplest. ‘F’ in this gauge denotes 'Full', and ‘E’ stands for 'Empty'. Unfortunately, when one is too focused on the road, they can miss where that needle is located in this gauge. To avoid such situations, car manufacturers have installed warning lights. If you notice it is blinking, immediately fill your car tank.

3. Temperature Gauge

From the name itself, you can figure out its function. This particular dashboard meter measures the engine coolant. When you start a car, the gauge will first display it is cold and then rise. If your car signals a rising temperature, it is better to pull over and let the engine cool down. Continuing to drive with an overheated engine can cause permanent damage to the car.

How to Read a Temperature Gauge?

In older car models, this was simply denoted with hot or cold signs. It is now changed to a thermometer symbol, but not all cars come with a temperature gauge. Instead, they now have a temperature warning light that glows when the engine overheats. You must let your engine cool down in situations like this by making a pit stop.

4. Tachometer

Unlike other dashboard gauges, a tachometer is the least used. However, tachometer readings are essential in cars that need a manual transmission. This helps the driver know the right time to change gears. Monitoring a tachometer also helps maintain fuel efficiency along with the best acceleration. Another purpose of a tachometer is to warn if the engine is pushed roughly.

How to Read a Tachometer?

The function of this gauge is to measure how fast the engine turns RPM or revolutions per minute. So, on the dashboard, you will find single-digits displayed along with “x 1000”. Thus, indicating you need to multiply the number displayed by 1000. With a higher RPM reading, more fuel is consumed. So, the best reading is when the RPM is lower and consistent to help the engine operate at an optimal level.

5. Voltmeter

Voltmeter provides information on the battery health of a car. Unlike the other digital dashes, not all passenger cars have this gauge but contain a low-battery warning light. If the voltmeter lights up in any condition, it indicates something is wrong with your vehicle’s electrical system.

How to Read a Voltmeter?

Most vehicles nowadays contain a 12-volt electrical system. Therefore, when a car battery is fully charged and functional, it must read 12.5 volts when the engine is not running. On the other hand, if the engine is running, its alternator will recharge the battery. Therefore, if you notice a drop in the voltmeter, the car will not start.

6. Oil Pressure Gauge

As the name states, the oil pressure gauge measures fuel consumption. Oil is responsible for running all its other parts. It is never a wise decision to drive a car with a lower fuel level as it can damage your car’s engine. Lower oil pressure can occur in instances if there is any serious leakage. Another possibility is that the fuel is full of dirt, making it difficult to flow.

How to Read an Oil Pressure Gauge?

Previous automobile models used to have a dial displaying oil pressure. However, newer models now have a warning light on the dashboard that marks the oil pressure levels. You can measure this in pounds per square inch or psi. Whether in an older car or new, if you find the low oil pressure signal is on, you must opt for car servicing.

In case any one of the gauge lights is not working, you can follow these steps:

Step 1: Find the defective gauge light and locate its sensor.

Step 2: Disconnect it from the sensor.

Step 3: Connect the sensor to the grounded connection.

Step 4: If it works, place the sensor back. You can also ask an expert to fix it if you are unable to.

Step 5: If there is a loose sensor connection, you just need to reconnect it.

In scenarios when the dashboard gauge lights are not working, your intent should be to narrow down the following. You can check the following aspects to check for the cause:

• Find the vehicle’s fuse box, and locate the fuse for that instrument cluster. If you find a damaged fuse, replace it and check with the new fuse box.
• Check whether the instrument panel has power. 
• Look for a grounded connection if the instrument panel has some power.
• If nothing fixes the issue, you may need to replace the whole instrument cluster.

To wrap things up, dashboard gauges are the diagnostic tools that help a driver know about various functions of a car. It is possible that the car may not have all these gauges. Most passenger cars only contain a speedometer and a fuel gauge. Even some new car models contain some additional gauges as well.

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