Fuel Gauge Not Working Or Is Inaccurate? How to Fix it

You rely on your fuel gauge to inform you when it is time to top up. You would not be able to tell if your vehicle has enough fuel for you to drive home without it. You need to find out why the fuel gauge doesn't work or is incorrect if this critical piece of equipment fails.

You could certainly count how many miles you drive with every fill-up. But that is just the beginning. Learn how to identify the issue and solve it immediately. Let’s take a quick look at the most common reasons.

Índice de Contenido
  1. Five Reasons Why a Fuel Gauge Does Not Work Correctly
    1. 1. Defective Sending Unit
    2. 2. Circuit Issues
    3. 3. Bad Fuse
    4. 4. Broken Gas Gauge
    5. 5. Malfunctioning Instrument Cluster
  2. What is a Fuel Gauge?
  3. How do you test your fuel gauge?
    1. 1. Self-Test Instrument Cluster
    2. 2. Make sure to check Fuse
    3. 3. Examine Wiring
    4. 4. Test Sending Unit
    5. 5. Make sure to check the gauge
  4. Fuel Gauge Replacement Cost
  5. Fuel Gauge FAQs
    1. What fuse is there for the fuel gauge
    2. What is the best way to check fuel levels without using a gauge?
    3. What does F stand for in a fuel gauge
    4. How do you calibrate a fuel gauge?

Five Reasons Why a Fuel Gauge Does Not Work Correctly

A bad fuel level sender unit is the most frequent reason why a fuel gauge doesn't work or isn't accurate. You can also have bad wiring or an blown fuse. Damage to the fuel gauge can cause it to malfunction.

Below is a list that explains why the fuel gauge may not be working correctly or incorrectly.

1. Defective Sending Unit

Rusted Fuel Sender Unit

It is here that the entire process starts. Your vehicle's fuel tank level is monitored by the sending unit. This constant usage means it can wear.

The circuits could remain open even if contacts become worn. Depending on the configuration of the vehicle, the fuel gauge could think that the voltage feedback indicates the tank is empty or full. In this case, the gas gauge won’t change despite how much fuel is in the tank. 

Reported: Signs that a fuel-sending unit is not working properly

2. Circuit Issues

Broken Wirings

Fuel gauges run on electricity and require functioning circuitry and wiring. A fault could cause the fuel gauge not to work correctly if it isn't receiving enough voltage. An interrupted ground connection can sometimes cause issues.

But, corrosion or loose connections can cause issues. Because of constant exposure to elements, these defects most often occur in the connection to fuel pump module. 

3. Bad Fuse

Broken Fuse

A fuse is also used by the fuel gauge, along with electrical connections. You can find the fuse in the box located under the steering column or on the driver’s side of your vehicle. A fuse box is located under some vehicles.

It takes only a few minutes to check the fuse. You can find the map of fuses in the owner’s manual to determine which one runs the gas gauge. 

Although many cars are now equipped with integrated fuel gauges, there is no separate fuse in modern vehicles. It can still be worthwhile to check.

4. Broken Gas Gauge

While this defect isn’t as likely, it can still be the cause. There’s an internal circuit inside the fuel gauge that can fail. The needle may not read correctly if this occurs.

The gauge should be between half-full and full. This indicates that there is a problem in the circuit. If the gauge is not moving, it could be a short circuit. It’s unlikely that the gauge will ever move again until it is replaced. 

Unfortunately, gas gauges are often integrated into the instrument cluster in newer cars.

5. Malfunctioning Instrument Cluster

Newer cars have an instrument cluster that is an integrated part of the car's equipment. Instead of using multiple circuits, it’s all intertwined. 

This system could cause the gas gauge to malfunction if it fails. Unfortunately, this can be one of your most costly repairs. 

What is a Fuel Gauge?

Fuel Sender Unit

There are three essential parts to the fuel gauge that all function seamlessly. For information, the circuit and sender are what you will see in your fuel gauge. The gauge may not read correctly if any of these components fail.

Fuel pump modules include a fuel gauge send unit. The fuel level is read by most systems using a sending device that has afloat. The circuit is used to connect the battery with the gas gauge and sending unit, but there’s also a connection to the ground. The majority of them are grounded to the vehicle’s electrical system, while older models relied on the frame or body. 

You will only see the gauge in the instrument cluster. The instrument cluster displays the data that it has received, and shows you the remaining fuel in your tank. 

How do you test your fuel gauge?

1. Self-Test Instrument Cluster

Read your owner’s manual to determine if your instrument cluster has a self-test procedure. While every vehicle from the early 1990s has a procedure, it’s different with every make and model.

You might need to switch the headlights on/off several times as you push a button. In other cases it may also require you to change the ignition. You should be able to see that the fuel gauge goes through all the locations during this self-test. If it doesn’t, there is something wrong with the fuel gauge or instrument cluster.

2. Make sure to check Fuse

A simple test is to check the fuse. In some cases, the fuse will run multiple gauges, so you might notice something else isn’t reading correctly at the same time.

You should replace a blown fuse and test it again if possible. You might also have an electrical problem if your fuse keeps blowing. 

3. Examine Wiring

While checking all of the wiring isn’t difficult, it does take some time. Start at the fuel tank to inspect the wiring. Also, inspect the ground connections as they can be corroded by rain, snow, and salt. 

You can clean the connections if you find any corrosion. It is important to reattach it at the correct place. You should replace any broken wires. 

Also, you can ohm-measure the wiring of the gauge, and compare it with the measurements at the sender. It's very possible that there is an unconnected or open circuit.

4. Test Sending Unit

If all of the wiring looks good and there’s not an issue with the fuse, you have to move on to checking the sending unit. In some cases, it’s just the float that is broken. 

Set your multimeter at 0 ohms to test the sender unit. One probe should be placed on the sender terminal and the other one on ground. Your multimeter will change the resistance as the float is moved. The sending unit may have failed if the resistance does not change. 

It will be more difficult to test a send unit that has the fuel pump embedded into it. These must all be removed and replaced if they fail. You may have to pull the fuel tank off some cars to get to the sending unit.

5. Make sure to check the gauge

For older cars, you will need two terminals for the gauge. If the ignition has one terminal, the second is connected to the sender unit. The first is for receiving power. You should check continuity between the send terminal and connection to the tank. If you don’t have continuity, you need to find a break in the wiring. 

The resistance can be checked to see if the fuel gauge is working. This can sometimes be difficult with a modern vehicle because of the integral instrument cluster. You might need to disassemble the entire cluster to get to the gauge, which is why it’s best to carefully inspect the wiring and sending unit first. 

Fuel Gauge Replacement Cost

Fixing a fuel gauge problem can be expensive, depending on what the reason is. It could cost anywhere from $10 to $800. A blown fuse can be replaced for $10, and it is easy to do yourself. You can easily replace the fuel gauge if it is damaged for $50 to $200, provided you are able to do the work yourself.  The mechanic might charge you an extra $100- $200.

Replacing the sender unit is usually the most costly repair. Not only can the part be expensive, but it’s time-consuming to replace. Some car models require that the entire fuel tank be removed in order to get to the sender. You might pay $200 to $800 depending on the type of car that you have.

Fuel Gauge FAQs

What fuse is there for the fuel gauge

There is usually one fuse to protect the fuel gauge. There is likely to be one or more fuse for the instrument panel. There are usually only two wires between the sender and the meter that do not have fuses. Check your repair or owner’s manual if you are not sure if your car has a fuse for the fuel gauge.

What is the best way to check fuel levels without using a gauge?

You can check the fuel level by visual inspection, but you don't need a gauge. The easiest way to check your fuel level is to take off the cap of the tank. You can also use some kind of “dipstick” like a hose into the tank to measure it. The odometer can be used to determine the level of fuel in a fully-filled tank.

What does F stand for in a fuel gauge

The letter ‘F’ stands for Full, indicating that the fuel tank is full. You may also find the letter ‘E’, which stands for Empty.

How do you calibrate a fuel gauge?

Most modern fuel gauges you don’t have to calibrate. To calibrate a fuel gauge, however, it is necessary to use resistors.

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