Air-oil separator situated on the engine. This is the main central separator, for the additional breather separators see part number 99710713800.

The separator collects residual gases and vapours from inside the crankcase and feeds them back into the intake manifold where they can be burned in the combustion chamber. This reduces the overall emissions of the engine.

When the separator fails the vacuum in the engine crankcase will increase causing oil to be sucked into the intake manifold. The oil is then burned up in the combustion process, producing grey/blue smoke in the exhaust.

To fit:
911 (997) 3.8 C2S, C4S 2005-2008