Why is my Porsche 996’s exhaust emitting white smoke at start-up?

A common 996 fault is the failure of the air-oil separator, which can lead to oil being sucked into the intake manifold and result in damage to the catalytic converter or even hydraulic lock.

The most obvious sign that the air-oil separator is failing is white smoke at start-up and possibly also while idling. The engine will also start to run roughly and the check engine light may eventually come on, but it is sensible to seek advice from a Porsche specialist before that stage to avoid the risk of expensive damage to other parts.