While the most likely issues are minor, smelling gas in your car can also be a serious sign of danger. With that said, let’s take a look at some possible reasons why it might be lingering:
1. The Gas Cap Is Loose
A loose gas cap lets gas fumes escape the tank and seep into your car’s cabin. Thankfully, gas tank pressure is something your car monitors, so if the cap isn’t tightly sealed, the check engine light will come on.
The solution is as simple as re-tightening the cap, but it’s time for a replacement if it is cracked. Use a cloth or rag to temporarily plug the filler hole until you can buy a new one.
2. You Just Refuelled
If you just filled up, you may have spilled some gas. Look for signs on the side of your car and your clothes. The smell will disappear soon, but you may want to drive with the windows down for a while.
3. Your Car Is Old
This particular reason refers to how cars used to be built. If your car uses a carburetor instead of fuel injection, a slight smell of gas will always linger.
Now, as for some of the more problematic reasons you might smell gas, they are as follows:
4. Loose or Damaged Spark Plugs
A loose or damaged plug will create a loose seal for the combustion chamber, so gas will escape when your car runs. Check to see if all your spark plugs are tightly seated. If they are, check their condition. You may find that their rubber sealing rings are cracked or broken.
5. Broken Fuel Pressure Regulator
Your vehicle’s fuel pressure regulator is responsible for sending a specific amount of fuel to maintain an optimal fuel/air ratio in the engine. When the regulator breaks, it can’t regulate that ratio, sending too much or too little fuel. In the former case, the engine won’t be able to burn the excess fuel, causing unburnt gas to exit via the tailpipe.
6. Your Exhaust Is Leaking
Catalytic converters clean exhaust gasses as they leave the engine. If there’s a leak in your exhaust before the catalytic converter, you may notice a gas smell and increased engine noise.
7. Gas Leak
Though such an issue is uncommon, it’s incredibly dangerous if it is the cause of the gas smell. A gas leak source can be anywhere in the fuel system, be it a damaged gas tank, a leaking hose, or a faulty fuel injector. You might notice a puddle of gas under the car.
Leaking gas should be taken care of immediately, but don’t drive the car to your local shop — have it towed.
What to Do When You Smell Gas
Stop driving and inspect your vehicle for the source of the smell. Start simple, such as by checking the gas cap and looking for spills. If the cause is something easy, you can fix yourself, such as a loose spark plug, break out the tools and get to work, but if it’s more serious, like a gas tank leak or fuel pressure regulator failure, it’s best to leave the work to the professionals at your local shop.
Summary: There are plenty of reasons your car might smell like gas. Some may be relatively harmless. Others can be quite dangerous.