When it comes to diagnosing car problems, you always want to rely on a mechanic and his or her diagnostic tools and devices to actually pinpoint the problem; however, you can sometimes tell what is wrong with a car by certain odd smells or odours it produces. Many fluids and parts under the hood will give off very distinct odours when they leak, burn up or otherwise malfunction. Note a few of those odd smells you might notice when your car is in need of repair and what they might indicate.


If you notice what smells like sulphur, this often indicates a problem with the battery. If it's overcharged, it may begin to emit this sulphur smell as it operates. An overcharged battery is dangerous as it may have fumes that build up in the case, so it's good to have it replaced. The catalytic converter could also be clogged and need replacing; this is a type of filter in the exhaust system that filters fumes and emissions from the car's engines before they travel through the tailpipe. When this converter gets clogged, those fumes get trapped and you may notice a sulphur-like smell.

Burning wood

Your car probably doesn't have any wood parts under the hood, but when brake pads begin to wear down, they may start to smell like burning wood, especially as you apply the brakes. The corrosion and abrasion of the brake materials pressing against the rotors when those pads are very thin causes them to overheat, and they smell like burning wood.

Burning rubber

While the phrase "burning rubber" refers to fast starts that leave skid marks in the road, it's probably not your tyres causing the smell of burnt rubber from your car. The clutch is more likely the problem; it may be burning up from overuse and now needs replacing. If your car has an oil leak, this can also produce a burning rubber smell; the hot oil from the engine may be dripping onto a rubber hose and burning it away, causing this odour.

Mouldy smell

If the car smells like mould or mildew, this is usually a problem with the air conditioning unit or air circulation system. If there is a filter that needs changing or if condensation has built up in the unit, this can cause mould or mildew to grow and, in turn, actually circulate every time you switch on the dashboard fan. This system can be flushed and cleaned or it may need replacing altogether.

Take your car in to an auto shop so a mechanic can inspect it and give you a proper diagnosis.