Car Exhaust Smells Sweet? Here’s The Reasons and How to Fix it!

Typically, your car’s exhaust smoke should have a burnt fuel-like smell. However, the following sweet smells indicate something is wrong-

  • Maple Syrup
  • Butterscotch 
  • Cinnamon

Such a sweet smell coming from exhaust fumes usually means something could be wrong with the coolant liquid, also known as antifreeze. 

But different variants of the sweet smell could mean different things. We have listed below what the possible issues could be, and what you can do to fix them.

Car Exhaust Smells Sweet
Car Exhaust Smells Sweet

Types of Sweet Smells from Exhaust

Let’s learn about the different kinds of sweet smells from exhaust.

1. Sweet Like Maple Syrup

This type of smell usually means that there is a leak in your car’s coolant fluid. The head gasket of your engine might have a problem and be leaking the coolant into the cylinder. 

You might notice the smell of white smoke coming out of the engine after a cold startup. 

2. Smells Like Butterscotch

A butterscotch-like smell of exhaust also means that there is a leak in the coolant. 

Sometimes, hot coolant can leak and accumulate inside the heated engine block. This in turn makes the smell stronger, like burning sugar, or butterscotch.

3. Smells Like Cinnamon

A spicy yet pleasant cinnamon-like smell will come from the exhaust when there is a boil in the coolant of your car’s air conditioner. 

When the gasket head is cracked or broken, the coolant leaks and goes into the combustion chamber. This results in the exhaust smelling like cinnamon. 

Is Sweet Smelling Exhaust Something to Worry About?

Although the smell is pleasant, it is not a good sign for your car. Coolant in the car helps to regulate the temperature of the vehicle and prevents it from overheating and freezing based on the weather conditions. 

So if the exhaust smells sweet, that means the coolant is leaking and already spreading towards the combustion chamber. 

As the coolant eventually depletes, your car will overheat very quickly and can lead to a fire hazard. 

Car engines release a great amount of heat anyway. So, without a coolant to keep the temperature in check, it can easily catch fire on and cause an accident while driving.

What Causes the Coolant to Leak?

Leaks in the coolant occur because of problems with the –

  • Radiator
  • Head gasket
  • Hose connections
  • Cracks in pipes
  • Heater core

Let’s look into the details of these and how they can cause the coolant to leak out. 

1. Radiator Issues

The radiator is made of small metal tubes that can easily get rusted with the slightest amount of moisture. 

Sometimes dust and debris can also gather on the radiator, and the constant friction from those can cause cracks and holes in the front of the radiator. The coolant can then easily leak out from these cracks and into the combustion chamber. 

2. Broken Head Gasket Seal

The head gasket works to seal the cylinder head from the engine block. When something is wrong with the seal, the coolant will enter the combustion chamber. 

The coolant then mixes with the engine oil which results in reduced efficiency of the engine.

3. Loose Hose Connections

The antifreeze flows through many hoses around the engine, and those hoses are tightly closed off with clamps. 

But sometimes those clamp connections can get loose or even come off completely. That causes the antifreeze to flow out of the hoses and into the engine block.

4. Cracked Pipes

Apart from the clamps on the hoses becoming loose or undone, the hose pipes can even develop cracks and holes over time. The antifreeze can very easily escape through those cracks and reach the combustion chamber.

5. Faulty Heater Core

The heater core in the car’s HVAC system can become faulty and cause too much heat dissipation within the car. Overheating from the heater core can cause the coolant to leak.

Related Post: How Long Can I Drive With an Exhaust Leak

How Do You Find the Coolant Leaks?

Right when you smell the sweet exhaust fumes, you need to locate the exact place of the leak in order to fix it. Here are some ways to check for leaks:

Puddles Under the Car 

If you see a puddle of orange, lime green, pink, or turquoise liquid underneath your parked car, then that means the coolant is leaking. Look for the exact spot from where the liquid is dripping to find the source of the leak.

Inspect Hose Pipes 

Take a flashlight and look for any signs of cracked hose pipes. You will usually see the cracked hose pipes covered in brightly colored liquid, which is the antifreeze fluid. 

Check the Radiator 

Look carefully for leaks in the radiator by inspecting the drain plug and the hoses connected to it. If you see spots of colorful liquid in those areas, then there is a leak for sure. 

Examine the Coolant Levels 

After a drive and after the engine has cooled down, open your car’s hood and look for the coolant reservoir. If it reaches LOW quicker than it should, then be sure that it is leaking.

Check the Heater Core 

Lift up the carpet under the dashboard and see if it feels damp. If so, then the antifreeze is leaking because of the heater core. 

Related Post: Strong Exhaust Smell When Idling [6 Issues To Look Out For]

Is it Safe to Drive While Sweet Smelling Exhaust is Released?

Coolant leaks are never a good thing, even if it is happening slowly. It is strongly recommended to get the leaks closed and fixed at the first instance of the sweet smell you notice.

Leaking coolant means the car will get heat up and cause sparks in the engine, which is highly dangerous while driving. 

While fire hazards are already dangerous enough, coolant fluids are essentially very toxic in nature. By any chance, if it is inhaled or ingested because of a leak, it can cause severe illnesses. 

So, you should not save your car for another long trip after smelling the sweet exhaust. Contact a skilled car mechanic, and get the leaks inspected and fixed as early as possible. 


Although a sweet smell being released from your car exhaust can seem innocuous enough, the cause and effect is quite the contrary. 

The smell can range anywhere from being syrupy to spice-like to smelling like caramel candy. But this means one thing – your car’s coolant leaking and mixes with other compartments in your car’s engine. 

Coolant leakages are bad, as they can cause overheating and engine malfunction, and imminent accidents. So, the right thing to do is get the leaks inspected and fixed professionally as soon as you can. 

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