Smell in the car: coolant, gasoline, burning and chemicals
LLCAR Editorial Team · updated
If you notice a sharp fuel smell, smoke, or the smell of burning wiring, stop in a safe place, turn off the engine, and get out of the car. In other cases, write down where and when the smell appeared and what signs accompanied it.
Sweet coolant smell
If you smell coolant inside the cabin, open the windows and arrange an inspection. If the engine temperature keeps rising, an overheating warning appears, or there is steam, stop safely, turn off the engine, and call for help. Do not open the cap of the hot coolant reservoir.
Check the coolant level after the engine has fully cooled, the engine temperature, and any traces of fluid. If the smell comes from the vents, the windows fog up, or the carpet under the dashboard is damp, mention this at the service shop. It will help them check the heater and other possible leak locations.
Gasoline or exhaust
A persistent gasoline smell inside the cabin or near the car can accompany a fuel leak. Do not restart the engine. If you suspect a leak, arrange an inspection or a tow.
If you can smell exhaust inside, open the windows, stop in a safe place, and get to fresh air. Carbon monoxide has no smell of its own, so the absence of odor does not confirm safety. Ask for the exhaust system and the paths gases take into the cabin to be checked.
Rotten egg smell in the car
If the smell appears inside the cabin or suddenly gets stronger near the car, stop safely, switch off the engine and get out into fresh air. If you feel unwell, call emergency services. Until the source is identified, do not continue your trip. The smell fading on its own does not confirm that the danger has passed.
A sulfur smell sometimes comes from the exhaust. The condition of the catalytic converter cannot be determined from smell alone. Another possible source is a lead-acid battery, for example when it overheats or is overcharged. If the battery is swollen, leaking, or there is a sharp smell near it, do not touch it, do not start the car, and do not connect a charger or jump-start cables. Arrange assistance and a check of the battery and charging system.
"Pharmacy" or other chemical smell
Drivers may use this to describe the smell of a cleaning product, washer fluid, air freshener, or a liquid spilled in the cabin. Check whether it appears when the heater or air conditioner is turned on, after using the washer, after cleaning, or after recent repairs. Check for spilled product or an unclosed canister.
Similar smells can have different causes. For example, a GM bulletin for certain models describes a smell from the heater that drivers mistook for coolant. If the smell keeps recurring with no obvious source, tell the service shop where it comes from and under what conditions it appears. If your eyes or airways are irritated, get to fresh air.
Burning, rubber, or melting plastic
Note whether the smell is linked to braking, turning on a specific device, or load. If there is smoke, sparks, or an intensifying burning smell, keep away from the car and call emergency services. If you suspect a fire under the hood, do not open it.
Sources
Hyundai on what to do during engine overheating
Example of a GM bulletin about similar smells from the heater
Example of a Ford alert about fuel smell and fuel leak