You can drive, but do not put it off
Smoke from the exhaust
Visible smoke from the tailpipe. The colour is the clue: white, blue and black mean entirely different things.
You can usually get home or to a garage, but every day of delay adds to the bill.
What to look at in the live data
- Thick white smoke with a falling coolant level means coolant is getting into the cylinders. Watch the temperature: overheating often comes with it.
- Blue smoke means oil. Live data will not show it, but oil consumption between changes will.
- Black smoke means an over-rich mixture. Watch the fuel trims: they will swing deeply negative.
- White vapour on a frosty morning during warm-up is normal, not smoke.
Common causes, cheapest first
- Black: a clogged air filter, a lying air meter, a leaking injector.
- Blue: valve stem seals or piston rings; on turbo engines, the turbocharger.
- White: the head gasket. That one goes to a mechanic, and it cannot wait.
Codes that show up with this
These parameters in the reference
Short term fuel trim B1Long term fuel trim B1Coolant temperatureShort term fuel trim B2Long term fuel trim B2Commanded equivalence ratioO2 sensor B1S2 voltageDiesel particulate filter temperatureFuel injection timing
Lamps that may be on
Do it step by step
«Everything is fine here» is the most annoying phrase. A trip recording ends it.A report for the mechanic when the fault is intermittent
A symptom is not a diagnosis. The same sign comes from a dozen different causes — the readings are what tell them apart, not the feeling.
How the app helps
CarScan shows exactly these readings live, remembers the highest and the lowest value of the trip, and puts them into a report you can hand to a mechanic.