Propane Smell In Car: 9 Possible Reasons With Solutions

If you suddenly find a propane smell in car, you should be worried, its not a good sign at all. In this blog, we discuss what this could mean, and what you can do to fix it.

Imagine you are driving your car, and suddenly propane smell comes from your vehicle. You became worried and confused because of the gas smell.

Well, there can be various reasons behind the propane smell in the car. For instance, faulty spark plugs, loose gas caps, dirty oil filters, or bad exhaust systems can be the reasons for it.

If you do not know much knowledge about car parts, take your car to the nearest mechanic as soon as possible.

The mechanic will determine the root cause of smelling propane gas and make the necessary changes.

Propane Smell In Car

What Are The Possible Reasons For Propane Smell In Car?

#1. Faulty Or Loose Spark Plugs

The work of the sparkplug is to ignite the air-fuel mixture inside the combustion chamber. It indicates these sparkplugs are fitted directly into the combustion chamber.

But the wires and plugs can get damaged with time and result in misfiring or gas leakage.

Again there are sealing washers in the sparkplug to prevent fumes from going out of the combustion chamber.

But when the sparkplugs are not tightened up to the correct torque, fumes may escape from the combustion chamber and goes into the car cabin.

Thus a propane gas smell comes from your car, which is dangerous.


  • Remove each sparkplug and check its coils and wires. If they are damaged, then replace them with a new ones.
  • Check the torque of each sparkplug. If the sparkplugs are not adequately tightened, then use a ratchet and socket to do it.

#2. Loose Gas Cap

Most of the time, you try to close the gas cap tightly after filling the fuel in the gas tank.

But sometimes the gas cap can be loose or not closed properly, and thus you smell propane gas. Additionally, you will smell propane gas if the cap is corroded or broken.

A propane gas leak is not good. Inhaling low concentrations of propane gas is not much harmful.

But higher concentration can be dangerous, and you will experience difficulty breathing, vomiting, headache, and other health issues.


Open the car hood and Inspect the gas cap as soon as you smell propane gas from your vehicle. If it is missing, then look over the engine compartment.

Some car drivers accidentally forget to close the gas cap. Driving in such conditions can spill all the oil over the engine compartment, which is dangerous.

Again if the gas cap is there but is poorly damaged or corrupted, then it’s best to replace it with a new gas cap.

Depending on the vehicle model type, it will cost you between $10 to $20.

#3. Damaged Fuel Lines

The gasoline from the fuel tank goes into the engine by the fuel lines.

If there is a crack in the fuel lines, there will be a leakage of fuel, which may seep into the car cabin.

Thus propane smell can come from your vehicle.


Inspecting the fuel lines may be challenging for you. Take your vehicle to the mechanic and if the fuel lines are damaged, replace them.

#4. Issues In EVAP(Evaporative Emission Control System)

Few amounts of gasoline from the fuel tank get evaporated with time. If they are released directly into the atmosphere, it can increase air pollution.

So vehicles are nowadays equipped with EVAP. Whenever the gasoline evaporates from the tank, it moves to the canister (a part of the EVAP).

The canister has activated charcoal which stores the gasoline vapors till the opening of the purge valve.

The ECM controls the purge valve, and when the valve opens, the gasoline vapors move to the engine and burn like regular fuel and provide power to the engine.

But when there is an issue with the EVAP system, the fuel vapors can escape into the atmosphere and seep inside the car cabin.


Check the EVAP system thoroughly and if the canister or purge valve is damaged, replace it with a new one.

#5. Exhaust Leakage

Exhaust leak is one of the most common reasons for propane gas smell.

If the exhaust leak is close to the engine and before the catalytic converter, the fuel can seep into the passenger compartment by the HVAC lines.

It even releases heavy smoke from the vehicle’s tailpipe, which is not good for the environment.


  • Listen to the sound of the engine while accelerating. If the engine sounds louder than usual, then there can be a possibility of an exhaust leak.
  • If you hear a loud ticking noise while accelerating your car, then there can be a possibility that the exhaust leakage is present closer to the engine.
  • If unsure about the exhaust leakage, put a thick towel over the tailpipe and put your hand over it. Don’t try to escape the exhaust gases into the atmosphere. If you don’t feel any pressure, then there can be a leakage in the exhaust system.
  • If your vehicle has two exhaust tailpipes, then take the assistance of someone to check the exhaust leakage.

#6. Faulty Oil Filter

The work of an oil filter is to remove dust, dirt, and various impurities from the oil before it moves to the engine components.

But when the oil filter goes bad or is blocked, a gas smell can come from the car.


Inspect the oil filter; if it’s too dirty, clean it. You can even replace the oil filter, which will cost you between $25-$30.

#7. Faulty Oxygen Sensor

A faulty oxygen sensor can also be the reason for the gas smell from the vehicle. All vehicles are equipped with oxygen sensors in the vehicle’s exhaust system.

The work of this sensor is to detect the amount of oxygen present in unburnt fuel and provide information to the ECU.

In short, these sensors will let the car computer know whether the air-fuel mixture is lean(too much oxygen) or rich(less oxygen).

The ECU will adjust the air-fuel ratio accordingly, and thus vehicle can provide the proper amount of power to the engine.

But when the oxygen sensors go bad or burnt, it can result in engine overheating and low fuel economy, and in the worst cases, the catalytic converter can get damaged.

The fuel vapors can even enter the car cabin, and a gas smell comes from the vehicle.


Modern vehicles are equipped with four oxygen sensors. Check each of the sensors and replace them with a new one if damaged.

#8. Issues In The Oil pan

The oil pan is the reservoir to store oil in the car. The oil pump draws oil from the oil pan, and then the oil moves to the filter.

The filter removes the dust, dirt, and various impurities, and then the oil moves to various engine components to provide adequate lubrication.

But if the oil pan is damaged, you will have fuel leakage. The leakage oil comes in contact with fuel, which may be the reason for the propane gas smell from the vehicle.


Check the oil pan; if it’s damaged, you must replace it. Replacing the oil pan will cost you between $100 to $500.

#9. Issues In Oil Cap

If the oil cap is cracked or damaged, you will have a gas smell inside the car cabin. Secondly, the O rings of the oil cap can get damaged with time.


Check the oil cap; if it has cracks, you must replace it. Secondly, if the O rings are flat, you must buy a new one.

Frequently Asked Questions

#1. Why do I smell propane but no leak?

There can be various reasons if you smell propane gas inside the vehicle but has no leaks.
The rubber hoses on your car’s valves like cylinder valve can wear out with time, allowing a small amount of fuel to escape.
If your engine doesn’t run effectively, you will inhale a gas smell inside the car.
The hoses in some engines will shrink slightly on colder days and allow little fuel to go outside. But once the car gets warmer, you will no longer have a gas smell.
The older vehicles have carburetors which have a small amount of fuel for starting your car. But if the carburetor is improperly sealed, it will allow fuel vapors to escape outside.

#2. Is it safe to drive a car that smells like gas?

Your car will not blow up if you drive a car that smells like gas. But you will experience other issues like black smoke from the tailpipe, oil drippings, a drop in fuel economy, and reduced gas mileage. So, it’s best to fix your car as soon as possible when it smells like gas.

#3. Is it safe to smell propane fumes?

Propane vapors are not poisonous. However, it is an asphyxiating gas. Inhaling many propane fumes can cause headaches, vomiting, and, worst cases, affect your lungs.

Wrap Up

A gas smell coming from the car is not good. You will not only inhale harmful odor gas but also experience reduced gas mileage and black smoke from the tailpipe, which is not good for the environment.

Take your vehicle to the mechanic to detect the root cause for the propane smell inside the car cabin, and if required, you have to replace a few parts of the car.

Thank you for reading this article.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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