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A gas gauge is vital for proper car operation. It indicates the level of gas in your car’s tank and alerts for a refill.
Running low on gas before refilling your tank can negatively affect your car.
It can cause the fuel pump to pick deposits, which clogs the fuel filter, injector, and fuel pump in the fuel sending unit.
A common side effect is the gas gauge needle going up and down and not reading correctly.
How A Gas Gauge Works
The meter in the gas gauge depends on the circuit and the sender to deliver information. If one or more of these components fails, the meter could read incorrectly.
The gas gauge sending unit is a part of the gas pump module. Most systems are designed based on a delivery unit that has a float that allows the fuel level to be read.
The circuit has the function of connecting the battery with the meter and the sending unit. However, there is a connection to the ground.
They are usually grounded in the car’s electrical system, whereas the older models rely on the body structure.
Inside the instrument cluster, you can see the gas gauge, indicating how much fuel is in the tank.
The gas gauge may vary in behavior due to external circumstances, such as driving on a slope or cornering.
It was widespread in older cars, although now they have walls in the tank to reduce the movement of gasoline and avoid erroneous readings.
What Causes A Gas Gauge To Go Up And Down?
A faulty gas gauge in the car won’t only annoy you but may also cause many other problems. It will make it impossible to tell exactly how low you are on fuel.
To prevent a sudden shortage, you would have to keep track of the miles you have traveled since your last fill.
So, it is essential to make sure of, at all times, a perfectly working gas gauge.
Your gas gauge is going up and down? Below are some of the causes and possible solutions:
Sender Issues
Most times, when a gas gauge needle goes up and down, the sender is the problem.
The gas gauge sender transmits information to the gauge about the amount of gas in your tank, but it is not immune to failure.
When your car has a faulty gas gauge sender, the data may not be transmitted accurately.
The main symptoms of a faulty fuel gauge include erratic behavior in the empty or overfull reading.
The fuel delivery unit may be where the whole process starts.
When the vehicle is not running, the sending unit is in charge of continuously monitoring the level of gasoline inside the tank.
Due to its permanent use, this part may suffer premature wear.
Fixing A Faulty Sending Unit
Fixing this part of the gauge is a bit expensive, labor cost being the most of the expense. So, it is wise to learn to self-diagnose and fix your gas gauge’s sending unit.
It will save you a lot of money if you feel okay doing it. Now, get your repair manual out and fix it!
Self-Check
To diagnose the sending unit accurately, you will need a multimeter, a full tank of gas, a system cleaner, and your car’s make and model’s standard resistance value (this can be found in the repair manual).
Check the car’s resistance with the multimeter, and compare the result with the standard resistance.
If the resistance value is a few ohms less than the original value from the manual, then the sending unit is the source of the fluctuation.
A quarter of the time, this process fixes this issue while there is a possibility it won’t.
In this case, corrosion around the float of the sending unit is inhibiting its functionality. A good scrubbing with the system cleaner will get the sending unit back to work.
If this doesn’t work for you, carefully remove the sending unit and replace it or get your car to a mechanic for repairs.
Circuit Issues
While loose connections and corrosion can cause breakdowns, these problems commonly occur in connections to fuel pump modules due to constant exposure to the elements.
Aside from electrical connections, the fuel gauge uses a fuse. It can be found in the box under the steering column or on the driver’s front side of the car.
Specific vehicle models may have a fuse box under the hood.
Checking the fuse is very practical and easy; it only takes a few minutes.
It is best to investigate the car manual where the fuse map indicates and thus find out the one corresponding to the gasoline meter.
Nowadays, most modern cars do not have a separate fuse when the fuel gauge is integrated, and it is best to check.
Self-Check
On sighting the fuse, check it carefully. If it’s blown, replace it, your gauge should be fine.
If the gauge’s needle is still going up and down after the replacement, it’s possibly a different issue.
Failure Of The Gas Gauge
Indeed, this fault is unlikely; however, it is not ruled out that it could be the reason. There is an internal circuit in the fuel gauge that may be faulty.
The needle goes up and down to read any level if that happens.
The meter between midpoint, full or empty, could be a circuit throwing error. On the other hand, if the needle is stuck or empty, the circuit has a short.
Unfortunately, the fuel gauge in modern vehicles is integrated into the instrument cluster.
In the event of instrument cluster system failure, the fuel gauge may malfunction and need to be replaced.
The cause can be as simple as a voltage issue in the car’s gauge. Follow your repair manual in steps to remove the instrument cluster in your vehicle.
Self-Check
Check on how to remove the car’s instrument cluster from the dashboard. When done, test the gauge with the multimeter; the voltage after the test should 12V.
If the voltage value is lesser, your gauge possibly has a fault. All you need to do is replace the gauge.
Gas Gauge Goes Up And Down – Conclusion
Fluctuation in a gas gauge should not be overlooked or ignored. It could be harmful, causing minor to fatal problems while driving.
It is advisable to fix the fault as soon as you notice it to avoid any undesirable issues. You can do this yourself with help from friends or family if you are comfortable with it.
If not, get the car to a mechanic soon for repairs.
Patrick started his love affair with cars in his childhood. Over the years, he claims a sturdy hold on his driving skills, along with a thorough understanding of cars. We can expect some interesting, holistic, and pleasurable blogs with his flair for writing and his love for cars.
Being a car enthusiast, Patrick has experience comprising of two decades in which he has ridden some of the meanest and strongest machines in the automotive industry. His previous avatars include an automotive professional, photographer, and journalist, and you will certainly experience the roundness of experience in his piece on this site.
In his second decade of reviewing cars and analyzing tools, Patrick is all set to give you convincing, reliable, and the latest information regarding what’s happening in the automotive industry. Currently, he owns a BMW Z3 but cannot get his eyes off Aston Martin DB5. He is a car enthusiast; he loves cooking and listening to music, especially jazz. Here are some of the pieces written by our ace author.
