White smoke from the exhaust
Thin white vapour on a cold morning that disappears as the engine warms is just condensation. Thick, sweet-smelling white smoke that continues is burning coolant.
AreaExhaust & smells
UrgencyHigh
Can I keep driving? Limit driving and diagnose promptly. Continued driving can cause damage, stalling or limp mode.
Common causes
Condensation
Normal on cold starts and in damp weather; it disappears after a few minutes.
Head gasket failure
Coolant leaks into the cylinders. Look for falling coolant level and a sweet smell.
Cracked cylinder head or block
Same symptoms, usually after overheating.
Leaking EGR cooler (diesel)
Coolant enters the intake through the EGR cooler.
Diesel injection problems
Unburned fuel in a diesel can also produce white-grey smoke.
What to check
- Check whether the smoke stops when the engine is warm.
- Monitor the coolant level over a few days.
- Test the coolant for combustion gases (block test).
- Do a cooling system pressure test.
Related OBD2 codes
Repair guides
Other exhaust & smells problems
General guidance only. A qualified technician can confirm the cause; brakes, steering and fuel leaks should be checked professionally if in doubt.