Common Causes:
* Engine oil leak: This is a serious issue. Smoke will often be bluish-grey or white and may have a burning oil smell. The smoke could be coming from the engine itself (burning oil internally), or from a leak onto a hot exhaust manifold or catalytic converter. This is a significant problem that needs immediate attention.
* Coolant leak: White or light grey smoke, often with a sweet smell. This could indicate a leak in the radiator, hoses, or water pump. It might also be steam if the leak is small and only happening when the engine is cold.
* Brake fluid leak: This typically isn't visible smoke, but rather steam. Brake fluid is hygroscopic (absorbs moisture), and a leak onto hot brake components can cause visible steam. This is a serious safety concern.
* Power steering fluid leak: Similar to brake fluid, a leak onto hot components can cause steam or light smoke. This will likely have a slightly sweet smell.
* Electrical short: Smoke could be caused by an electrical short in the wiring harness, especially if it smells like burning plastic or rubber. This is a fire hazard.
* Exhaust leak: If the smoke is coming from near the exhaust manifold or pipes, it is likely an exhaust leak. The smoke will likely be black, grey, or white, depending on fuel mixture and other factors.
Less Common Causes:
* Burning debris: Something like leaves or other debris could have gotten lodged near the exhaust or engine bay and is burning.
Determining the Source:
To pinpoint the source, you need to:
* Observe the color and smell of the smoke: This gives crucial clues to the source.
* Check fluid levels: Inspect engine oil, coolant, brake fluid, and power steering fluid levels. Low levels strongly suggest a leak.
* Listen for unusual noises: Rattling, squeaking, or hissing sounds can indicate a leak or other mechanical problem.
* Inspect the area visually: Carefully look for any visible leaks or damage around the engine, wheels, and undercarriage.
Important Note: If you see smoke coming from your car, pull over safely and turn off the engine to prevent further damage or a potential fire. Do not continue driving. Have it checked by a qualified mechanic as soon as possible.
