Why The Gas Needle Goes Up And Down?

The gas needle is a simple mechanism that starts from the E when the tank is empty to F when the tank is full. It, not a direct mechanism, it uses electricity to make gas needle goes up and down. As a result, the gas needle in the car, whether digital or analog, informs the driver how much fuel is present in the car’s fuel tank.

This gas needle has two parts are the indicator on the dashboard and the sending unit in the tank. A bad sending unit is the most common cause of gas needle goes up and down. Before we go for the causes and the solution of the gas needle problem, it’s better to understand how its works.

Why Does The Gas Needle Goes Up And Down?

Fuel needles work by measuring the voltage across the variable resistor within the detecting system to determine the fuel level. But said resistors vary in direct proportion to the amount of fuel in the tank. To do this, the fuel tank is floating at one end of the lever arm and the slider running over the strip of the resistor at the other end. This is known as the sending unit. This sending unit is the virtual part of every vehicular fuel tank and works flawlessly.

Because the float moves vertically with the changing fuel level, the opposite end of the lever slides across the resistor causing the change in the voltage supply at the needle. As a result of a direct response, the indicating gas needle goes up and down to the appropriate position on the gas needle.

What Are The Common Reason For The Gas Needle Issue?

The gas needle is a very simple mechanism bur each part of the component is essential to the function. In this article, there are a few symptoms written below to know its cause. And if you notice any of these symptoms, you might have the issues.

1. Problem In Sending Unit

Sending units is the most common cause of gas needles go up and down. When the vehicle is in motion, the sending unit is in constant motion,  constantly rubbing the variable resistor. Over time the contact can wear, leading to an open circuit. The gas needle might interrupt the voltage feedback from the dead sensor as full or empty. no matter what will be the actual level of fuel.

2. Problem In The Circuit Problem

Loose connection or corrosion in the circuit can be the reason particularly at the fuel pump module, which is exposed to the elements. Depend on the location of the fault, the fuel sender must not have a source voltage. As a result, the gas needle may have no fuel sender voltage or the ground for either one may be interrupted.

3. Failure In Gas Needle

It is a very uncommon problem in the gas needle of the car. In case of internal circuit is faulty, the gas needle function in one of the positions such as either in between FULL and EMPTY or HALF and EMPTY. In the case of the internal circuit get shorted, it will continuously fluctuate between FULL and Empty. If the internal circuit is open, the gas needle will sit at an EMPTY position and never move toward the FULL.

4. Failure In Instrumental Cluster

This problem is the very least uncommon problem and most expensive than the above cause. The instrument cluster is the fully integrated circuits. In case of the problem is noticed at the instrument cluster, you have to replace the whole unit with the new one otherwise gas needle goes up and down continuously.

How To Fix The Gas Needle Issue?

A gas needle works through a series of an electrical connections from the sending unit to the gas needle. When one of their connections gets malfunctions, the gas needle stops working. With the help of few basics tools, you can start to fix the gas needle and avoid costly repair.

1. Fuse Box

Turn the ignition switch on and off several times, and watch the needle properly so that if it moves or not. In case it does not move, you must have, you have a blown fuse case and have to replace it. By observing in the manual book, you can easily find where the fuse box and replace it as soon as possible.

2. Grounding Wire

Attach the negative jumper cable to the car terminal frame and the positive jumper cable to the grounding wire of the sending unit. you notice that the gas needle is working. If this happens, you have to replace the grounding wire.

3. Gas Needle

Disconnect the wire which is attached to the fuel sending unit and look at the gas needle. The EMPTY reading of the gas needle says that the gas needle is faulty and needs to replace. The FULL reading of the gas needle says that sending unit is faulty and needs to be replaced.

4. Wire Connection

By consulting the user manual book, you have to verify all the wiring that is connected with the gas needle. To see the wire connection, remove the dashboard to access the instrument cluster. The position of the dashboard varies from car to car.

How Much Does It Cost To Replace The Gas Needle?

The cost to replace the gas needle will vary between 17$ to 170$. This cost includes the labor as well as replacing parts cost. To prevent paying a huge labor price, we suggest fixing the issue by yourself.


Now you can fix the issue whenever you notice that the gas needle goes up and down, working intermittently or filed. It is highly recommended when you can’t fix relace the gas needle under the hand of expert mechanics. It will save you from the trouble of running out of gas or constantly tracking the miles you have driven since your last fill-up. Whenever you prepare for fixing the gas needle by yourself, make sure to wear a piece of safety equipment. The safety equipment is Mechanics gloves and safety glasses.

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