If you notice a sweet, syrupy, or honey-like smell in or around your car, it usually means coolant (antifreeze) is leaking. Coolant contains ethylene glycol, which has a distinct sweet odour. While it may not seem serious at first, a coolant leak can quickly lead to overheating and severe engine damage if not addressed.

What does a sweet smell in your car mean?

The smell is caused by coolant escaping from the cooling system. This could be from a leaking radiator, heater core, hose, or gasket. When coolant drips onto hot engine parts, it vaporises, releasing a sweet odour that often enters the cabin through the vents.

Common causes of a sweet smell in the car

• Leaking radiator or radiator cap
• Cracked or loose coolant hoses
• Faulty heater core
• Blown head gasket
• Coolant reservoir leak

Why do you need to fix this problem quickly?

Coolant leaks reduce the system’s ability to regulate engine temperature. If the coolant level gets too low, the engine can overheat, leading to warped heads, gasket failure, or complete engine damage.

How do you know when to get it checked?

You should book an inspection if:

• You notice a sweet smell inside or outside the car
• The heater isn’t working properly
• The engine temperature gauge shows overheating
• You see coolant puddles under the car
• The coolant warning light is on

What happens during an assessment?

A mechanic will:

1. Check coolant levels and inspect for visible leaks
2. Pressure test the cooling system
3. Inspect the radiator, hoses, and coolant reservoir
4. Check the heater core and head gasket for leaks
5. Advise on necessary repairs and refill coolant as required

How much does it cost to fix?

Costs depend on the source of the leak. Hose or clamp repairs may cost $150–$350. Radiator replacement typically costs $500–$1,200. Heater core or head gasket repairs can range from $900–$2,500+.

Is it unsafe to drive with a sweet smell?

Yes. Driving with a coolant leak risks sudden overheating, which can cause catastrophic engine failure. If you smell coolant, the car should be inspected as soon as possible.