Why Is Smoke Coming From My Car Exhaust?

Whether you drive a petrol, diesel or hybrid vehicle, your car will expel smoke through the exhaust pipe.

In a healthy engine, you shouldn’t see much visible smoke, as there is not enough oil burning to produce any.

For this reason, if you see smoke coming from your car’s exhaust, it generally indicates that you have a problem with the engine or the exhaust system. The colour and cause of the smoke varies depending on the problem – but you can never ignore a smoking exhaust.

White Smoke Coming From Car Exhaust

Steam coming from the exhaust could be caused by condensation in the exhaust pipe. However, a car exhaust that produces white smoke - even when the vehicle is fully warmed up - could indicate that the vehicle is experiencing head gasket failure. The head gasket is designed to stop coolant from leaking out of the water jacket or cooling channels.

A coolant leak can cause serious damage to the engine, so it is important that you stop the engine if you notice white smoke coming from the exhaust. Be sure to regularly check your engine’s coolant levels to ensure that your car has the appropriate level of engine oil.

A problem with the engine will need to be addressed by a professional garage as soon as possible.

Black Smoke Coming From Car Exhaust

If you notice black smoke coming from your exhaust, this can be a sign that your engine is injecting more fuel than air into the combustion process, rather than an equal amount. This could mean that the air filter is blocked, or that there is an issue with the fuel injectors or fuel-pressure regulator.

In diesel cars, black smoke can indicate that the car’s diesel particulate filter (DPF) has become blocked, in which case you may need to book in for a professional DPF clean.

Black smoke is generally nothing to worry about as it is usually a rare occurrence, but an exhaust which regularly produces black smoke could signal there is a fault with the engine.

As previously stated, any issue with the engine should be investigated by a professional garage immediately.

Grey Smoke Coming From Car Exhaust

Grey smoke coming from the exhaust could be the result of PCV valve failure or excess oil, or even a transmission fluid leak in the case of automatic cars.

If the grey smoke is constant, then this needs to be inspected by a professional garage as soon as possible. There could be an issue with a jammed turbocharger or a leaking engine seal if this is the case.

Blue Smoke Coming From Car Exhaust

Blue smoke is usually accompanied by a certain smell, and normally indicates that a repair is needed. The problem could relate to the turbocharger, if the car is fitted with one.

In older or higher-mileage cars, natural wear and tear can lead to the emission of such smoke. However, this could also be an indication of head gasket failure.

What Should I Do About Smoke Coming From My Exhaust?

If you are at all worried about the health of your vehicle, be sure to have your exhaust looked at by a professional garage in Otterbourne like Williams Garage. Certain issues such as an engine fault or a blocked DPF can result in MOT failure, so it is important that you book with a capable garage at the first sign of trouble. You can rely on Williams Garage to efficiently find and resolve any issue with your car’s exhaust.

To prevent these problems in the first place, and to stop any reoccurring, we recommend booking regular car servicing at our garage in Otterbourne. With regular servicing, you can ensure that these visible emissions are not a cause for concern.