White smoke from the exhaust
The buyer question: "white smoke from exhaust"
Stop driving if the smoke is thick or persistent, the temperature rises, coolant is disappearing, the engine runs poorly, or warning lights appear. Do not assume it is harmless vapor.
What could cause it
More than one problem can cause the same symptom. These are places to inspect, not a diagnosis.
- Normal condensation during a cold start
- Coolant entering the combustion or exhaust path
- An overheating or cooling-system problem
- A vehicle-specific emissions or engine condition
Safe things to check
Keep clear of moving parts, hot components, and traffic. Use the owner's manual for vehicle-specific instructions.
- Observe whether it clears as the engine warms and whether the odor is sweet or unusual
- Watch the temperature gauge and warning lights
- Check coolant only when fully cool and never open a hot pressure cap
Stop and arrange professional help when smoke persists, the engine overheats, coolant is low, or the exhaust odor is strong. Keep people away from hot steam and traffic.
What a mechanic may check
A technician may inspect coolant level and pressure, scan the engine, check combustion gases or compression where appropriate, and inspect the cooling and exhaust systems.
If you are considering this car
Persistent white exhaust smoke is a reason to stop the purchase process. Ask for a cold start, a written diagnosis, and an independent inspection before you consider the car.
Questions for the seller
- Does the smoke clear after warm-up, or does it continue under acceleration?
- Has the vehicle lost coolant or overheated?
- What tests ruled in or out an internal coolant leak?