Skip the auto shop - Our mechanics make house calls

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
Icon-warranty_badge-02

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.

GET A QUOTE

More related articles

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,...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance Related Trouble Codes: P2158: Vehicle Speed Sensor B P2160: Vehicle Speed Sensor B Circuit Low P2161:...


Related questions

Q: I installed new front air shock last night now I am getting a "cat fault" reading on dash display

Hooking the battery positive cable up first is actually recommended. then there is no chance of arcing your wrench against a metal part of the car. I always disconnect the ground cable first and re-connect it last. It's possible your...

Q: Purge control solenoid stuck open, hard to start after refuling

Hello. If the computer is saying that the purge valve is stuck open it is usually because there is an EVAP leak in the system. If the purge valve is new I usually check the wiring and the signal going...

Q: All kinds of problems with the electronics

This problem could be related to the immobilizer function of the alarm system, or could be related to the engine or vehicle ground circuits. If the Check Engine Light is illuminated, a local mechanic with an advanced scan tool (like...