Possible causes
Bluish smoke and oil consumption
Bluish smoke with a smell of burnt oil can mean oil is getting into the combustion chambers. Oil consumption between changes usually goes up too.
Thick white smoke from a warm engine
White smoke with a sweet smell, together with a falling coolant level, is a reason for an urgent engine check. Driving with this sign is dangerous for the engine.
Black smoke
Black smoke usually comes from a mixture that is too rich: a problem with the air or fuel supply. On diesel engines a short puff of dark exhaust under sharp acceleration can happen, but constant black smoke is not normal.
What to tell the mechanic
- The colour of the smoke and whether it appears with a warm engine.
- Whether the oil or coolant level is dropping.
- Petrol or diesel engine, and whether power or fuel consumption have changed.
What you can do
If the coolant level drops or the engine temperature rises along with white smoke, stop and do not drive on. In other cases, note the conditions in which the smoke appears and show the car to a mechanic.
Where the check starts
The mechanic finds the exact cause during the inspection.
Frequently asked questions
Is white vapour in winter a fault?
No, if it disappears once the engine is warm and has no smell. It is condensation in the exhaust system.
Can you tell from the colour what needs repairing?
No. The colour points to a group of possible causes. The actual fault is found during engine diagnostics.