AOS Oil / Air Separator. Porsche 987/981 Boxster / 987/981 Cayman / 982 GTS 4.0L

Oil / Air Separator.
A crankcase air-oil separator (AOS) that traps oil droplets and vapour from the engine’s blow-by gases and returns cleaned air to the intake system while keeping oil inside the engine’s lubrication system.
Sold individually. It is recommended to also inspect and, if necessary, replace associated hoses and seals when fitting a new separator to ensure full system integrity.

Fits:
Porsche 987.2 Boxster 2009 - 2012
Porsche 981 Boxster 2012 - 2016
Porsche 981 Boxster Spyder 2016>>
Porsche 982 Boxster GTS 4.0L 2017>>
Porsche 987C.2 Cayman 2009 - 2012
Porsche 981C Cayman 2014 2016
Porsche 981C Cayman GT4 2016>>
Porsche 982C Cayman GT4 4.0L 2017>>

Diagram ref no 16

This air-oil separator is an replacement unit designed to filter crankcase blow-by vapours on Porsche engines, separating oil mist from the air before routing clean air back into the intake or ventilation system.

Over time AOS units degrade - internal baffles can become clogged, seals can fail, or plastic can crack due to heat cycles. A faulty or clogged separator may allow oil vapour into the intake, causing:
•  Increased oil consumption and oil-soaked intake/tracks.
•  Blue or grey smoke from exhaust, rough idle, misfires or poor running.
•  Sludge or carbon buildup, fouled sensors, and potential engine damage.

Replacing with a correct fresh separator restores clean crankcase ventilation, keeps oil inside, and helps maintain reliable performance and engine health.

You should replace the air-oil separator when:
• You notice oil in the intake system, oil residue around intake or throttle body, or excessive oil consumption.
• The separator is showing signs of age: cracks, hardened plastic, degraded seals, or clogging.
• Your engine exhibits excessive smoke, rough idling, or misfires potentially related to intake contamination.
• Carrying out engine maintenance, PCV servicing, or installing new hoses/seals.
• The separator hasn’t been replaced for many years or high mileage - preventive maintenance helps avoid more serious issues.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

0PB115099A

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