Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. What Does the Fuel Cap Warning Light Mean?

What Does the Fuel Cap Warning Light Mean?

What Does the Fuel Cap Warning Light Mean?

As you may know, your car pumps liquid gasoline from the fuel tank to the engine to be ignited by the spark plugs. Your car may also contain some gasoline that has evaporated which is then sent to the engine to be used up. The evaporated gas gets collected in a separate tank called the charcoal canister. Once certain driving conditions are met, a valve opens to the engine and the fuel vapors get mixed in with the rest of the fuel being burned.

In order for this fuel system to work properly, it needs to be sealed from the outside air so that nothing escapes. Most fuel caps have a rubber O-ring to prevent vapors escaping when the cap is secured. As you drive, your car is able to monitor the system for any possible leaks in the system and display a warning light on the dashboard if a leak is detected.

What the fuel cap indicator means

Simply put, if your fuel cap light is on, it means that the computer has detected a leak in the system, typically from a loose gas cap. If this light comes on while driving, pull over in a safe spot and re-secure the cap. Continue driving normally with the light illuminated and it should go off within a day or two. If the light doesn’t turn off, inspect the gas cap for any damage and replace it if necessary.

A leak present somewhere else in the system can also trick the computer into thinking the gas cap is leaking. If the gas cap looks okay and the light does not turn off, have a certified technician investigate the issue and determine the cause.

Is it safe to drive with the fuel cap indicator on?

The main thing you may notice if the light is on is a slight reduction in performance. With less power, your engine has to work harder to get up to speed. As a result, your gas mileage will diminish slightly. On top of that, you are likely releasing harmful gases into the environment.

Without properly working EVAP systems in every car, our quality of air would be much worse due to the hydrocarbons released from the gasoline. Maintaining your EVAP system also ensures that you are getting the most out of the fuel you buy.

Our certified technicians are always available to assist you with diagnosing any problems related to your fuel cap indicator light.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...

Related questions

Q: Engine mangenent light all of a sudden. Limp mode

Hi there. Typically, when the engine management light comes on, there is a correlation issue between the APP (accelerator pedal position) sensor and electronic throttle control TPS (throttle position sensor). When this occurs, the PCM (powertrain control module) puts the...

Q: Car is difficult to start and keep running after adding fuel.

Your car has a small purge valve that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the...

Q: Q: What does the door ajar light mean?

The door ajar light is located on the instrument panel, or on the driver information center (DIC) if your car comes equipped with the uplevel cluster. When the door ajar light is illuminated, one of your vehicle’s doors is not...