Smoke and smells
Burning smell in the car: what it could be and what to do
A burning smell has several sources and each smells different: clutch (acrid, after a hill start), brakes (metallic, after long descents), oil on the exhaust, coolant (sweet) or plastic and wiring (electrical). Burning plastic, or any smell with smoke, is the most dangerous.
Stop as soon as it is safeSmoke and smells
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Do not keep driving. Stop as soon as it is safe and find where it comes from. If it smells of burning plastic or wiring, you see smoke or it comes from under the hood, switch off the engine, get out and call for assistance. If it comes from the brakes or the clutch, let them cool before carrying on more gently.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Overheated clutch: hill starts or a lot of manoeuvring with the clutch half engaged; if it recurs for no reason, it is slipping.
- Overheated brakes or a sticking caliper: a smell after a long descent, or one wheel much hotter than the others.
- Oil on the exhaust: a leak dripping onto the manifold or the exhaust pipe.
- Coolant: a leak evaporating on the hot engine; it smells sweet.
- Electrical fault: a cable or component melting; it smells of plastic and is the most urgent.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: What is a particulate filter and how long does a regeneration take? How often should you run diagnostics on your car?
Car system: Engine and lubrication
What you can check yourself
Note when it appears: after a descent, after a hill start, in traffic or when switching on the heater.
With the car stopped, see whether smoke comes from the hood or a wheel, without touching anything hot.
If it is a wheel, holding your hand near it without touching shows whether it gives off much more heat than the others.
With the engine cold, look for oil or coolant on the engine and under the car.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: coolant and oil temperature, and whether a particulate filter regeneration is in progress on a diesel.
Frequently asked questions
It smells of burning after coming down a mountain road. Is that normal?
It may be overheated brakes if you braked a lot. Use lower gears to hold the car and let them cool. If it smells without heavy braking, have the calipers checked.
Can a new car smell of burning?
The first miles can smell a little from coatings on the exhaust and brakes. It should not last or come with smoke.
It smells of burning when I turn the heater on. What is it?
The first time after months it can smell of dust. If it smells sweet, the heater matrix may be leaking; if it smells of plastic, stop and have it checked.
Keep reading
- Engine and lubrication: how they work and what fails
- Slipping clutch: symptoms, causes and what to do
- Noise when braking: what a squeal or a metallic grinding means
- Engine temperature warning light on: what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means