If your gas cap light or ‘Check The Engine’ light is on, typically, it indicates the gas cap of your car is faulty or not secured properly. So the first thing you have to do before asking for professional assistance is to check the gas cap’s condition. And then replace it if needed.
Other than that, many other problems can make this light turned on. For example, faulty or cracked fuel tank or oxygen sensor, worn out spark plug/wire, faulty catalytic converter, fuel filler neck, etc. To know more about why is my gas cap light on, keep reading further.
Why Is My Gas Cap Light On?
As you might already know, when you start your car engine, liquid gasoline gets pumped into the engine from the fuel tank. Also, sometimes the engine uses some already evaporated gasoline. That particular evaporated gas is saved in another tank named a charcoal canister.
So when the engine gets started, the gas of these two tanks gets mixed and gets burned. But to keep this working properly, the total fuel system needs to be air-tight and make sure that no gas escapes from it. That is where the fuel cap or gas cap comes from.
When the cap is secured, it ensures that no vapor escapes with its rubber O-ring. However, you will get a notification with the warning light if there is any leak in the system. Your car system has a leak detection system that does the warning task for you.
Fuel Cap Indicator
As we mentioned before, the fuel or gas cap indicator light of your car gets turned on when there is a leak detected in your fuel system. And primarily, that directs to your loose gas cap.
If you are in such a situation while driving, try to pull over immediately in a safe place. And then make sure that the gas cap is secured properly. This should just turn the light off in a day or two.
But sometimes the gas cap might get damaged. In that case, the indicator light will remain turned on. Then you will have to replace the gas cap with a new one.
However, sometimes the leak might be somewhere else. And yet the leak indicator system can direct you to think that the problem is with your gas cap light. In that situation, changing the fuel cap will not solve your problem.
Just check if everything is okay with the gas cap or not. Then call for some professional assistance to troubleshoot and find out the cause.
Is it safe to drive when the gas cap light is on
There are no safety concerns to drive when the gas cap light is on. So you can drive safely until the gas cap is fixed or replaced, or further initiatives are taken. Here are the things you need to know about this:
- Harmful gas will not be delivered to the passenger cabin, even if the gas cap is not properly secured.
- Even though the engine might have to work slightly harder. It will not harm your engine in any way.
- In your car, there is a pre-built flapper valve. And that will prevent fuel to prevent flowing out of the fuel tank.
Your car might release harmful gases, mostly hydrocarbons, into the environment, if the gas cap is not secured properly. And that happens when you do not have a proper EVAP (evaporative emission control) system.
EVAP system protects the fume from gasoline spilling out into the environment. But that is not the only thing. It also ensures that you are using most of the fuel you have. And thus, it prevents the wastage of fuel as well.
Other Reasons Behind Gas Cap Lights Being On
Apart from the loose gas cap, there are some other reasons why the gas cap light gets turned on.
- Faulty or cracked fuel tank
- Faulty oxygen sensor
- Worn-out spark plug/wire
- Faulty air flow sensor
- Faulty catalytic converter
- Fuel filler neck
How to Reset the Warning Light Gas Cap?
When you see the gas cap light on, you can either resecure it manually or wait for the car system to reset it automatically. Or if you have a modern car that has an OBD-II (Onboard diagnostics) system, you can just scan for any problem related to engine and emissions-related components and reset that manually.
Here is how you can do it:
Step 1: Turn the Engine off
Before you go any further with the procedure, make sure that the engine is turned off. If your car has a locking gas cap door, push the button to unlock it. You will find it right on the floorboard on the driver’s seat side. Or it can be located right beneath the steering column as well.
Step 2: Open the gas cap door
Now open the gas cap door and twist the gas cap handle counterclockwise. That will just unscrew it and then remove it.
Step 3: Replace the gas cap
Now you can clean and replace the gas cap. And if you find any issue or damage in the gas cap, replace the gas cap with a new one. Whether you replace the thread with a new one or an old one, it will just seal the thread properly.
Now twist the gas cap handle clockwise to screw it tightly. You will hear three clicks and that will ensure that the gas cap is placed properly.
Step 4: Close the Gas cap
Now close the gas cap and start your engine. Drive your car for a day or two. The gas cap light should be turned off. If it does not, it means that the cap was secured perfectly. And the problem is somewhere else. To troubleshoot the problem, call a professional mechanic and find out the solution.
Step 5: OBD II scanner
Now if you have a modern car that has the OBD II scanner feature on it, use that to find the problem. To do so, just connect the OBD II scanner to the OBD II port.
You will find the port right beneath the steering column. It might look like a computer printer port. On the scanner, push the reset button. And that will just clear the system.
Frequently Asked Questions
Where is the gas cap sensor located?
The gas cap sensor is located either on the top of the tank or inside the tank. This particular sensor is part of the EVAP system (evaporative emissions system) and detects leaks in the faulty gas cap or faulty fuel tank by reading the pressure in the system.
How much is a gas cap sensor?
The replacement of the gas cap sensor is a pricey task. It might cost between $260 to $300. The labor cost for the replacement should be around $150. Whereas the part alone can cost $110 to $130. The price can vary for different types of vehicles.
How do I know if my gas cap is bad?
If you can not secure the gas cap properly, there is a chance that the gas cap is faulty. In that case, it will not tighten properly and remain loose.
There are many reasons why is my gas cap light on. But the first thing you can do is to check the gas cap and see if that is in the right shape or not. If not changing the gas cap would be the most economical thing you can do. But if it is okay, go to a mechanic and see what he has to say about it.