Why Is My Gas Light on When I Have Gas and How To Fix It?

“Why is my gas light on when I have gas?” is a common complaint among drivers as they try to figure out what is wrong with their vehicle. This can be frustrating as many drivers tend to rush to gas stations to get some fuel only to find out that they had enough all this while.

Usually, this occurrence is indicated by the yellow light that illuminates a fuel pump on the dashboard. This article will discuss what triggers this light and propose solutions to fix the issue.

What Illuminates the Gas Light When There’s Enough Fuel?

The gas indicator light can illuminate when there’s enough fuel in the tank if there’s a problem with the fuel level sensor. The fuel level sensor determines whether the fuel tank is full or the quantity is not enough to power the vehicle.

It works by measuring the voltage across the variable resistor to read the level of fuel in the tank. The fuel sensor is comprised of three major parts, which are a variable resistor, a wiper, and a float switch. When any part is damaged, it affects the entire system, which gives false readings hence illuminating the low fuel light. The float switch travels across the surface of the fuel and is connected to the variable resistor via a metal rod.

The variable resistor measures the differing heights of the fuel and its end is attached to the ground. Now, when the level of fuel changes, the wiper travels across the variable resistor, which changes the voltage across the metal rod connected to the float switch.

Thus, the wiper moves to low resistance when the tank is full and high resistance when the tank is almost empty. Since the fuel gauge is preprogrammed to understand this movement, it’ll send signals to trigger the low-gas indicator light when the fuel in the tank is low.

– Wrong Readings From a Broken Variable Resistor

The variable resistor determines the level of fuel inside the tank and features a variable resistance board and a needle. On the needle are tiny lines which are essential in communicating the exact level of the fuel to the fuel gauge.

These lines can wear out over time due to their constant usage or be damaged by bad fuel. When that happens, they give wrong readings, which can cause the light to illuminate.

– Inaccurate Signals From the Faulty Float Sensor

Also known as a fuel-level sensor, the float sensor works in tandem with the variable resistor to monitor the level of the fuel in the tank and relay it to the fuel gauge. If it gets broken, it won’t collaborate properly with the variable resistor and this could result in wrong readings. A broken float sensor could be the reason why the low fuel light comes on and off.

– A Defective Fuel Gauge Receiving the Wrong Signals

Sometimes the problem may not lie with any of the above but with the fuel gauge itself. The fuel gauge tells the driver the amount of fuel left in the vehicle by displaying it on the dashboard. The gauge takes its information from the fuel tank sensor, which it uses to determine the level of the fuel. A malfunctioning fuel gauge will illuminate the low-gas indicator light as it reads the content of the fuel tank as low, even if it is high in reality.

– A Clogged Ventilation Hole in the Fuel Tank

The tank ventilation hole allows air into the tank to counter the air pressure from outside the tank. This prevents the buildup of pressure within the tank which can damage it. Thus, if this hole is blocked, it can cause the tank to shrink and damage the needle that helps in reading the level of fuel. This results in a faulty reading of the level of fuel, which can cause the low-fuel indicator light to come on even if the tank has enough gas.

How To Fix a Low-Gas Indicator Light With Adequate Fuel

To fix a low-gas indicator light with adequate fuel, you can try fixing the variable resistor, repairing the clogged ventilation hole, fixing the issues causing a faulty fuel gauge, and fixing the light itself. We will have to identify the main cause of the light turning on first.

Take note that when the low-gas light comes on, you can usually drive between 90 and 130 kilometers before the car finally stops and you’ll have to refill the tank. It’s better to calculate the journey and the amount of fuel you’ll need to avoid any troublesome situations. Also, ensure you carry extra fuel with you.

Turning off the low-fuel indicator light on your dashboard depends on the kind of issue that is causing. Therefore, we’ll discuss the solutions to the specific problems highlighted in the paragraphs above and offer ways to prevent the light from illuminating in the future.

– Fixing the Variable Resistor

Repairing the variable resistor is quite easy, but first you need to be sure it is the component causing the low-fuel indicator light to illuminate. To do this, you’ll require an ohmmeter; a device used to measure electrical resistance. Use the instrument to measure the electrical resistance between the two terminals of the variable resistor and record the value. Now, compare that value with the full and half tank values in the car manual.

If the values are different, then it means the variable resistor has developed a problem. To fix it, clean the resistor with an abrasive and rust cleaner and measure the resistance again. If you get the right values, then the problem is solved. However, if your values are wrong, then the variable resistor needs a replacement.

– Repairing a Clogged Ventilation Hole

Since the blocked ventilation hole causes the tank to shrink, it’ll be difficult to fix it. We recommend that you purchase a new fuel tank cover and ensure that the hole isn’t clogged again.

Also, since the shrinking of the tank bends the needle that moves across the resistance board, make sure you straighten it. This should solve the problem and turn off the low-fuel indicator light.

– Fixing the Various Issues Causing Faulty Fuel Gauge

A faulty fuel gauge has several causes and each cause has its own unique solution. For example, a blown fuse that forms a part of the fuel gauge can give wrong signals. In this case, you only have to replace the damaged fuse with the new one and you’ll be on your way. However, if the electrical connections that make up the system come loose, all you have to do is to tighten them and you’re good to go.

If you spot some corroded wires, all you have to do is to clean them with a solution of salt and vinegar. However, if the wires are damaged, then you’ll have to replace them to ensure a properly functioning fuel gauge.

– Fixing the Illumination of the Low-Gas Indicator Light

The best way to fix the low fuel level warning light when there’s adequate gas in the tank is to prevent it from happening. To achieve this, make sure you use high-quality gasoline in your vehicle because such products come with negligible quantities of impurities.

Low-quality fuel is notorious for containing all kinds of impurities that could damage components of the fuel sensor. It also has a high quantity of water that can aid the corrosion of the tank’s metallic part.

Also, avoid driving for long distances when the low-fuel indicator light accurately indicates that the gas in the tank is low. Doing this could cause the fuel sensor to rub against the thick nature of the fuel at the bottom of the tank and lead to several damages.

The thickness of the fuel at the bottom of the tank could also form a sludge-like substance and this spells doom for the sensor. The idea is not to wait until the low-fuel indicator light comes on before you refill your fuel tank.

Another preventive measure is to constantly check the fuel ventilation hole at the top of the tank to ensure it’s not clogged. When you find some debris around the hole, wipe it with a drive cloth and ensure that the dirt doesn’t get through the hole into the fuel tank. Also, it is not advisable to squeeze in a few more liters of gasoline when the fuel tank is full after the pump clicks off. Doing this may trigger the low-fuel warning light, so stop filling the tank after the tank is full.

Frequently Asked Question

– How Do You Reset Your Low-Gas Indicator Light?

To reset your low-gas indicator light, drive to a fuel pump and fill your tank. If the light refuses to go off, then try servicing your fuel-level sensor or check the gas tank hole for any blockages. If all these fail, then allow a professional mechanic to assist you.

Conclusion

A low-gas indicator light usually indicates that there’s not enough fuel in the tank, but sometimes it comes on even when the tank is full, indicating an underlying problem.

Here is a handy summary of some of the major underlying problems and how to fix them:

• The tiny lines on the needle of the variable resistor can wear out over time or be damaged by bad fuel, forcing the device to give wrong readings, which will need to be replaced.
• A faulty fuel sensor can also send wrong signals to the fuel gauge, triggering the low fuel light and will need to be serviced or changed.
• When the fuel ventilation is clogged, it increases the pressure within the fuel tank, causing it to shrink. The way to fix it is to change the fuel tank cover.
• A damaged fuel gauge can also trigger the low-gas indicator light and you can only repair it if you know the exact cause of the damage as explained in the article.
• To prevent the low-gas indicator light from illuminating when there’s enough fuel, ensure you use only high-grade fuel and don’t allow the fuel to run too low before refilling the tank.

Also, constantly check the ventilation hole for debris and wipe it off if you see dirt accumulating around it. If you’ve done all these and the gas light still doesn’t turn off, then drive to the nearest mechanic for assistance.