A gas smell in car usually means fuel vapor or liquid fuel is escaping somewhere, so treat it as a safety issue until you find the source. Some causes are minor, but others can start a fire or expose you to harmful fumes. The steps below help you decide what to do now.
A loose gas cap is the cheapest thing to check first when you notice a gas smell in car. A fuel line leak is different, and it calls for a professional repair, often by tow.
This page is general information, not a diagnosis of your vehicle. If you smell fuel near the engine or exhaust, contact a qualified mechanic before driving.
Is a Gas Smell in Car Dangerous?
Yes, it can be. Cars.com’s gas smell guide describes a leak in the high-pressure fuel lines that can spray fuel as a mist, and that spray can catch fire, especially near the hot exhaust. A fuel odor inside the cabin can also come from fumes entering through the ventilation system. The smell alone does not tell you how serious the leak is.
Exhaust is the second risk with a gas smell in car. Exhaust fumes contain carbon monoxide, and carbon monoxide has no smell. A gas odor therefore cannot tell you whether the car is leaking exhaust, which is why both fuel and exhaust problems deserve prompt attention.
What to Do If You Smell Gas While Driving
If you notice a gas smell in car while the engine is running, turn the engine off and arrange a tow instead of driving on. Follow these steps in order:
- Pull over in a safe place away from traffic, open flames and smoking.
- Turn the engine off and keep everyone out of the car while you check the area.
- Wipe off any gasoline on your skin or clothing as soon as possible, because breathing gas fumes is harmful.
- Check that the gas cap is tight and in place, but do not restart the engine to test it.
- Call a tow truck if you see fuel leaking or the smell is strong, since a professional must make a fuel line repair.
Common Causes of a Gas Smell in Car
The most common causes are a loose or missing gas cap, a leak in the evaporative emission system, a leaking fuel line or vent hose, and fuel left on your hands, clothing or the car after refueling. Cars.com also lists fuel injectors, spark plugs, the fuel-pressure regulator and a clogged air filter as possible sources. Any of these can produce a gas smell in car, so compare the symptoms in the table to narrow down what you are dealing with. A rich mixture from a faulty regulator or clogged air filter can also store a code such as the P0172 rich mixture code.
| Cause | What it looks like | What to do |
|---|---|---|
| Fuel line leak | Strong gas odor, fuel spray or mist near the engine | Turn the engine off and call a tow |
| Loose or missing gas cap | Fuel odor after refueling or when parked | Check that the cap is tight and in place |
| EVAP system leak | Fuel vapor smell, sometimes with the check-engine light on | Have a mechanic test the system |
| Leaking fuel-tank vent hose | Gas odor from the fuel system | Have a mechanic inspect and replace the hose |
| Improperly sealed injector or spark plug | Gas odor that reaches the ventilation system | Professional diagnosis and repair |
| Missing oil-fill cap | Fuel fumes drawn into the cabin through the ventilation | Check the cap after the engine has cooled |
| Rich fuel mixture | Fuel smell from a faulty pressure regulator or clogged air filter | Mechanic diagnosis, usually not serious but still needs repair |
Loose Gas Cap and EVAP Leaks
A loose or missing gas cap lets fuel vapor escape from the fuel system, and a cap that does not seal can also trigger the check-engine light for an evaporative system fault. The evaporative emission system routes fuel vapors from the tank to the engine, so a leak anywhere along that path can cause a gas smell in car, and a stored fault may show up as the P0442 small EVAP leak code. A loose cap alone can trigger a warning, as the guide on the check engine light and a loose gas cap explains.
The U.S. Department of Energy’s maintenance guide notes that a loose gas cap could be something minor, but it could also reduce fuel economy, increase emissions and lead to costly repairs later. Check that the cap is secure after every fill-up, because it is the simplest check for a gas smell in car, and watch whether the smell fades over the next few drives. If it does not, the leak is probably elsewhere in the system, and a mechanic should test it.
Exhaust Leaks and Carbon Monoxide
A small exhaust leak can let carbon monoxide build up inside the car, and the CDC describes this gas as odorless and colorless. The CDC also says it kills without warning and is found in fumes produced any time fuel is burned in cars or trucks, so a gas smell in car deserves a second look even when it seems faint.
Follow these rules when the engine is running, from the CDC carbon monoxide guidance:
- Never run a car inside an attached garage, even with the garage door open.
- Open the door of a detached garage to let in fresh air before you start the engine.
- If only the tailgate is open, exhaust from the back of an SUV or car can be pulled into the cabin.
- Do not rely on your nose, because carbon monoxide gives no warning smell.
Smell After Refueling or Parking
A gas smell right after refueling can come from fuel on your hands, clothes or shoes, which Cars.com lists as a non-leak cause. Remove it as soon as possible, because the same source warns that breathing gas fumes is harmful. Wash your hands and change clothing if fuel touched them.
Puddles under the car help you narrow down the cause of a gas smell in car. Clear liquid or rainbow-tinted stains are likely fuel, while air conditioner water is normal and does not smell like gas. Cars.com also notes that a missing oil-fill cap can let fumes into the cabin through the ventilation system. Check that cap only after the engine has cooled.
When to Book a Mechanic or Tow
Have the car towed if you can see or smell a fuel leak, and book a mechanic when a smell persists after you have checked the gas cap. Cars.com advises that when a leak is not near the engine or exhaust, the car should be towed rather than driven to a service center. If a gas smell in car comes with any of these signs, call a professional:
- A strong gas odor that continues after the gas cap has been checked.
- The check-engine light comes on along with a fuel smell.
- Clear or rainbow-tinted liquid is dripping from under the car.
- A fuel smell from the engine bay, where injectors and high-pressure lines sit.
Cars.com says that EVAP leaks, injector seals and pressure regulators are best diagnosed by a professional, because the smell alone cannot show which part is failing. If the check-engine light is lit, the service engine soon light guide explains what that lamp means.
Frequently Asked Questions
Can a loose gas cap cause a gas smell in car?
Yes. A loose or missing cap lets fuel vapor escape from the fuel system, and it can also cause the check-engine light to come on. Check that the cap is secure first. If the smell continues after that, have a mechanic test the evaporative emission system for leaks.
Is it safe to drive with a gas smell in car?
Not when the smell is strong or you suspect a fuel leak. Sprayed fuel can ignite near hot exhaust, so turn the engine off and arrange a tow. A faint smell that started after refueling may only be fuel on your clothing or shoes, which you should remove right away.
Can you smell carbon monoxide?
No. The CDC describes carbon monoxide as an odorless, colorless gas that kills without warning. A gas smell cannot confirm or rule out carbon monoxide in the cabin, so treat exhaust problems seriously and never run a car inside an attached garage.
Why does my car smell like gas when parked?
A gas smell in car while parked can come from the fuel system, such as a leaking vent hose or an EVAP problem. Cars.com says these causes are best diagnosed by a professional. Check the gas cap first, then have a mechanic inspect the system if the smell continues.
Does air conditioner water smell like gas?
No. Cars.com notes that air conditioner water is normal and does not smell like gas. Clear or rainbow-tinted liquid under the car is more likely fuel, so find out where it comes from before you drive.
Should I see a mechanic for a gas smell in car?
Yes, if the smell continues after you checked the cap, if the check-engine light comes on, or if you see fuel leaking. The smell alone cannot show which part is failing, so a professional diagnosis is the reliable next step.
When the source of a gas smell in car is unclear, stop driving the car, keep it away from open flames, and let a professional check it before you use it again. Treat any fuel leak as an urgent repair rather than a cosmetic problem, because the smell alone cannot tell you how serious it is.
