Our cars can communicate problems in many different ways, from warning lights on the dashboard to noises or vibrations. Sometimes though, the only symptom is a strange smell, coming either from the engine, exhaust or inside the cabin. 

In this article I’ll run through some of the most common odours you are likely to smell, and what they mean. 

My Car Is Making A Strange Smell, Is It Serious?

Without identifying what is causing the smell, and exactly what it smells like, it's impossible to say, but one thing’s for sure, you shouldn’t ignore a funny smell coming from your car. 

Whilst it could be something as simple as forgotten groceries under a seat, it could also be something as serious as a blocked exhaust system or dangerous fuel system. 

Whilst this guide will be a handy tool to potentially identify the problem, we always advise taking your car to a qualified mechanic as soon as possible.

Common Car Smells and Their Causes

Burning Smell 

Whether in a car or not, an unexpected smell of something burning is always cause for concern. 

There could be any number of sources of this smell from a vehicle, including melted or burning wiring, an overheating engine, cooked brakes or a failed bearing somewhere attached to the engine, such as the AC system or alternator.

What to do if your car smells like burning

Pull over as soon as it's safe, turn off the engine and exit the vehicle. Whilst standing well back, examine the front and rear of the car to see any obvious evidence of smoke.

Don’t open the bonnet or boot without first taking precautions to check for fire. If the smell persists, but there are no obvious signs of fire, look over the car more closely, trying to identify the source of the smell. 

If the problem persists, call emergency roadside assistance before continuing the journey.

Sweet Smell

A sweet smell is often indicative of a coolant leak, it can be made worse by the fluid dropping onto a hot surface such as the exhaust manifold.

Whilst it may not present an immediate issue, you should at the very least check your cars coolant level.

If the level is low or the problem is persistent, ensure to keep it topped up before having it fixed as soon as possible.

How to Fix Car Sweet (Coolant) Smell

If your coolant is leaking and causing a sweet smell to enter the cabin, it's important to have it fixed as soon as possible.

Coolant leaks are difficult to fix without the correct tools and equipment, so it's best to take it to a qualified mechanic as soon as possible.

Rotten Egg Smell From Car

The smell is a result of sulphur dioxide, usually from a clogged catalytic converter. This is one of the most difficult smells to deal with as it can be extremely pungent and unpleasant. 

Take your car to a mechanic as soon as you notice an egg-like smell from your car, sulphur dioxide l is dangerous to our health, and the fact you can smell it at all means you are breathing it in!

How to fix an egg smell from your exhaust

Whilst the catalytic converter being blocked is usually the cause of the smell, it is not always the source of the problem. Oftentimes the cat can be blocked due to an over fuelling issue, caused by a bad sensor or faulty fuel system. 

To remedy this problem, an inspection of the car is needed, an ECU scanner would help to diagnose the problem at its source, then the offending sensor/injector/filter replaced.

Musty Smell From Inside the Car

A musty smell is generally caused by damp and/or stale air. 

This can be through lack of use or a faulty window or door seal allowing moisture into the cabin. The smell can often be trapped in the numerous soft furnishings including seats, carpets and headlining.

With modern cars being very well sealed from the atmosphere, any smell in the interior can be very apparent, but thankfully it is something you can try to tackle at home. 

How to remove musty smell from car

First try to identify any source of leaks, the common culprits are boot seals and door seals, but feel around the carpets and interior - particularly after it has rained for damp spots.

If there is no discernible leak coming in, you can try removing the smell. 

I always start by vacuuming out the carpets and seats, this gives you a chance to check under the seats too. 

If the smell is very bad, you may want to use an upholstery cleaner on the seats and carpet following the instructions on the bottle, and ideally sucking up excess moisture with a wet vacuum. 

Once cleaned, the car needs to dry out, if you or a family member has a dehumidifier, this is the fastest solution, leave it running inside the cabin for a few hours and check again. 

If not, a small fan with the windows cracked open will encourage airflow which will help out the drying process (don’t do this if it's raining, though!) 

Fuel Smell From Car

Whether your car is diesel or petrol-powered, smelling fuel at any time other than whilst filling up is cause for concern, in the best case scenario fuel is leaking and causing a danger to other road users, the worst case is much more severe. 

As soon as you smell a strong petrol or diesel smell inside the car, and it is not from a recent fill-up stop, assess the situation as soon as possible. Remove everyone from the car whilst doing so. If in any doubt call roadside assistance.

How to fix a fuel smell inside the car

If the smell appears to be coming from the front of the car, it’s possible there is a leak somewhere in the fuel system, such as at an injector or fuel rail. Do not attempt to fix this unless you are a qualified mechanic. A smell from the rear could mean a leaking or punctured fuel tank or fuel filter, again consult a professional for help.

Hot Oil Smell From Car Engine

If you are getting an oily, acrid, plastic-like smell coming from the engine, it's possible leaking oil is dripping onto something hot. This could be from something like a leaking turbo, oil filter housing or faulty PCV system.

The two main things to consider if you smell this is your health, and the engine’s oil level. The smoke will contain nasty compounds that are not good for you and your passengers, and the loss of oil could mean disaster for your engine too. 

How to fix burnt oil smell from car engine

This one is probably best left to the professionals, you could do some minor investigation by looking over the engine when its fully cooled down and the smoke and smell has gone, to see for any evidence of oil leaks. 

Take your car to a garage to have them look over the engine and ancillaries for leaks and drips.

How To  to Avoid Unpleasant Car Smells

Preventative maintenance is key to avoiding all sorts of problems, including mechanical and odorous issues. 

Here are my top tips for preventing problems, and smells from arising.

Regular Car Maintenance and Cleanliness

Cars are complex machines that require regular upkeep and maintenance, keeping on top of these is a good way to avoid unforeseen problems. Your car's manufacturer will list the service intervals in the manual, this is a great starting point for keeping track of maintenance.

Keeping your car clean is also a good way to avoid further issues, not only is it more appealing should you wish to sell the car, but excess dirt can hide problems that would otherwise be spotted early.

Check out our car maintenance guide for more information.

Importance of Regular Oil Changes

Engine oil is the only thing preventing your engine from excessive wear, it forms a lubricating layer on metal components that would otherwise rub together. Oil does degrade over time and with the usual heating and cooling cycles of using your car. 

This is why it's important to change it according to the manufacturer's recommendations or better, this usually means every 6,000miles.

Having work done on your car at regular intervals also allows you to monitor potential issues, such as excessive oil consumption.

Proper Car Ventilation

Just like in a house with stagnant air, damp and musty smells can build up over time if adequate ventilation is not provided. If a car is used daily, the action of entering and exiting, running the air conditioning and opening the windows should be enough to prevent a musty smell from developing.

However, if your car has even a small leak, or there has been a period of heavy rain, where clothes and shoes are bringing in moisture to the interior of the car, it may be enough to produce a damp environment. 

There are a few things you can do to help this, ensure the cabin air filter is changed frequently, and the blower is used on low even when not needed, this will bring in fresh air from outside. The air recirculation button should not be pressed.

Car Smells - What You Need to Know

So we’ve gone through all of the possible smells your car can make, in particular, keep an eye (or nose!) out for smells like burning, petrol and sulphurous/egg smells. 

These can pose an immediate danger to either you or your car.

Repair Your Car With Bumper

If you are noticing any of the smells we’ve discussed here, or have other faults that need addressing, Bumper’s zero-interest financing allows you to spread out the cost of car repairs and maintenance. Check here to find your nearest Bumper partner.

Author - Joseph Law

Joseph has been writing about cars for over seven years and writing for Bumper for over two, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his five cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.