- Oil leaking into the combustion chamber. This can happen due to a worn piston or piston rings, or a cracked head. When oil leaks into the combustion chamber, it burns and creates blue smoke.
- Incomplete combustion. This can occur due to a faulty fuel injector, a clogged air filter, or a misfire. When fuel is not completely burned, it can create blue smoke.
- Turbocharger problems. A failing turbocharger can cause oil to leak into the exhaust, which can then create blue smoke.
- Worn valve stem seals. Worn seals allow oil to enter the combustion chamber, where it burns and becomes visible as blue exhaust smoke.
- Coolant leaking into the combustion chamber. This can happen if the head gasket is blown, allowing coolant to mix with the engine oil. When this happens, the water in the coolant can turn into steam and create a white or bluish exhaust smoke.
