Fuel Low: What Does the Low Fuel Light Mean?

Reviewed by

Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on February 26th, 2024

Reading Time: 4 minutes
Summary
  • The low fuel level warning light turns on when there’s inadequate fuel in the gas tank.  It illuminates when a vehicle’s fuel tank is at around 10% to 15% of its maximum capacity.
  • The PCM monitors fuel level with the help of a fuel level sensor.
  • Once the warning light illuminates, it’s best to use the remaining fuel you have to find the nearest gas station.

Running out of fuel in the middle of a trip is something all drivers want to avoid. Luckily, modern vehicles have a low fuel level warning light that illuminates once there’s not enough fuel in the tank.

When Does a Low Fuel Level Warning Light Turn On?

This warning light found on your dash illuminates once there’s inadequate fuel in the gas tank.

The low-fuel warning light typically illuminates when a vehicle’s fuel tank is at around 10% to 15% of its maximum capacity. Once you see this light on your dash (knowing your tank isn’t full), it’s safe to assume that there is only one to two gallons of fuel left in your fuel tank. You’ll have to take your vehicle to the nearest gas station.

What Triggers the Low Fuel Level Warning Light?

The powertrain control module (PCM) can detect fuel levels with the help of a fuel level sensor. The mechanism usually has an arm that moves up and down. One end of the arm is attached to a resistor while the other end floats on top of the fuel in the tank. The PCM will interpret fuel level based on the position of the floating arm.

The powertrain control module (PCM) can detect fuel levels with the help of a fuel level sensor.

Is It Dangerous to Drive with a Low Fuel Level Warning Light?

Generally, it isn’t dangerous to drive even if your fuel level is low. However, if you continue to drive, you’ll eventually run out of fuel and get stuck in the middle of the road.

Once the warning light illuminates, use the remaining fuel you have to find the nearest gas station. Remember that your car can break down if you run out of fuel. Check out our article about the risks of driving with low fuel to learn more about it.

How Long Can You Drive With the Low Fuel Level Warning Light?

How far you can drive with an empty tank depends on what type of vehicle you own. Diesel trucks, for instance, still have around three to four gallons of fuel left when the gauge says Empty. That means you can still drive around 100 miles. Trucks with bigger tanks can go as far as 200 miles.

Why Is My Fuel Level Warning Light On Even If My Tank Is Full?

But what if your gas tank is full? If your fuel level warning light still illuminates even after filling up your gas tank, you’re probably dealing with a faulty part.

Here are some of the other issues that can cause your fuel level warning light to illuminate:

Blocked Fuel Tank Ventilation Hole

A blockage in the fuel tank’s ventilation hole can cause a fiberglass tank to shrink. The metal needle or wiper used to measure fuel can bend or break once this happens.

Damaged Variable Resistor

Corrosion can damage the small metal lines on your variable resistor. Aside from age, low-quality fuel and harmful additives can cause the materials on your resistor to corrode. So a failing resistor can also trigger the fuel level warning light.

A failing resistor can also trigger the fuel level warning light.

Anthony Harlin, ASE Certified Master Automobile Technician

Bad Float Switch/Sensor

Your fuel level light can also turn on if your float sensor is damaged. Once it fails, it’ll not be able to work with the variable resistor, resulting in accurate readings.

Malfunctioning Fuel Gauge

Aside from faulty sensor components, a bad fuel gauge can also cause your low fuel level light to illuminate. The most common reason why your fuel gauge fails is a bad fuel level sending unit.

Faulty wiring surrounding your gauge and fuel sender can also cause a similar issue. Get your vehicle checked by a trusted mechanic in case you notice symptoms such as erratic gauge readings.

What to Do If You Run Out of Fuel

Running out of fuel on a busy road makes you vulnerable to road collisions. If you know that your gas tank is almost empty, take the slow lane so that you can easily exit the road. A spluttering engine will die down anytime, so make sure that you stop at a safe spot where no other vehicle can bump into you.

After that, you can switch your hazard lights on to alert other drivers. Do this as soon as you notice the issue. It’s dangerous to get stuck on the road—-especially if it’s snowing or raining. Depending on where you’re at, you can opt to contact roadside services or walk to the nearest gas station. Don’t forget to lock your doors in case you decide to find a gas station near you.

How to Locate the Nearest Gas Station

If you’re unfamiliar with the place you’re in, you can still find a gas station easily as long as your phone still has reception. Google Maps, for instance, can show you the gas stations that are near your location. Using the filters, the map can even show you the gas stations you’ve already visited and those you haven’t yet.

Where to Get New Fuel Tank Components for Your Vehicle

It’s quite nerve-wracking to see your fuel level gauge sitting on the “empty” mark only to find out that you still have a tank full of fuel. It might seem like a minor issue, but such problems are better addressed as soon as possible.

Here at CarParts.com, fast shipping and high-quality parts are our top priority. Find all the fuel tank components you need from our website in a matter of minutes, and get your order delivered to your doorstep in as fast as two business days thanks to our strategically located warehouses across the US.

Shopping for parts from the comfort of your home is much more convenient thanks to our user-friendly website and mobile app. Simply use our vehicle selector to check for fitment, and place your order with just a few clicks.

Get the best deals online, and take advantage of our low-price guarantee. We source parts from today’s top parts manufacturers in bulk to pass on the savings to you.

Shop and order the parts you need today!

About The Authors
Reviewed By Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Tony Harlin is a Master Gas and Diesel Diagnostic Technician with over 18 years of experience. He works full-time at a large independent automotive shop as a driveability and repair technician working on all types of vehicles with a focus on diesels. ASE certifications include A1-A9, L1 and L2, as well as X1.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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CarParts.com Research Team and Anthony Harlin, ASE Certified Master Automobile Technician