Black, when accelerating
Check within a few days- Carbon build-up in the intake and EGR valve
- Injectors
- Boost leak or MAF sensor
The fault can get worse and more expensive. Drive carefully and book a diagnosis.
Smoke from the exhaust — what does its colour mean?
Smoke colour is one of the best clues when diagnosing an engine. Black smoke usually means too much fuel, blue means burning oil, and thick white smoke that doesn’t go away after warm-up means coolant getting into the cylinders.
Most common variants and causes
Bluish, the car uses oil
Check within a few days- Turbocharger
- Valve stem seals
- Worn piston rings — we check with an endoscope
The fault can get worse and more expensive. Drive carefully and book a diagnosis.
Thick white, coolant level drops
Avoid driving — call us- Head gasket
- Cracked cylinder head
- Engine overheating
Driving on may be unsafe or cause serious damage. Call us — we’ll advise whether to drive in or use a tow truck.
What you can check yourself
- Notice whether the smoke appears only when the engine is cold (steam — normal) or also after warm-up.
- Check the oil and coolant levels — are they dropping?
- Notice whether the smoke appears when accelerating or at idle.
- Check whether there’s an oily layer on the coolant.
How we check it in the workshop
We read fault codes, check the injectors and turbocharging and, if engine wear is suspected, inspect the cylinders with a camera (borescope) — without taking the engine apart.
This is guidance only, not a diagnosis. We’ll find the exact cause at our workshop in Bielany — you approve the quote before any work starts.
Frequently asked questions
White vapour from the exhaust in winter — is it a problem?
No, if it disappears once the engine warms up. Thick white smoke with a sweetish smell after warm-up is a warning sign.
What does blue smoke mean?
Burning oil: worn piston rings, valve stem seals or the turbocharger. A borescope inspection shows the cylinders without taking the engine apart.
Is black smoke from a diesel dangerous?
A puff under hard acceleration isn’t always a problem. Constant black smoke means a problem with injection, turbocharging or the EGR and needs diagnostics.
Other symptoms
Check engine light is onKnocking over bumpsCar pulls / steering off-centreBrake problemA/C not cooling or smellsCar won’t startRattling from the engineJerky gearbox or clutchEngine is overheatingPuddle under the car / leakCar jerks when accelerating
Not sure? Take the symptom test (2 clicks)