Crankcase Ventilation Fault
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A crankcase ventilation (CCV or PCV) fault occurs when the system that manages pressure and vapor inside the engine block malfunctions. The most common culprit is a failed pressure-control valve that allows oil mist to be drawn into the intake manifold and combustion chambers. This typically shows up as higher oil consumption, blue-tinted exhaust smoke, and a fouled intake system. Severity depends on your engine family and model year, as BMW sets different acceptable oil-consumption thresholds for turbocharged, naturally aspirated, and M engines.
What it feels like
The main warning sign is abnormal oil consumption between services. You may notice blue or white smoke in the exhaust, especially during cold start or when coasting. The throttle body and intake valves become coated with an oily residue, which can eventually degrade idle quality or trigger a check engine light. Some owners report a slight surge in crankcase pressure, which can contribute to oil leaks around gaskets and seals. In severe cases, the engine bay smells of burnt oil.
How to confirm it
- Pop the hood and inspect the intake manifold, throttle body, and intake piping for a heavy oil film or coating. A normal CCV system should not leave visible oil residue inside these passages.
- With the engine at idle, disconnect the crankcase ventilation hose and listen for abnormal hissing or feel for excessive pressure at the opening. Attach a low-pressure gauge to measure crankcase vacuum or positive pressure at idle and under load.
- Visually examine the CCV valve itself, the connecting hoses, and the diaphragm for cracks, blockages, or tears. Look for hardened or split rubber components and any sign of oil pooling inside the valve body.
- Review your service records and owner manual for the acceptable oil-consumption range on your specific engine code (N54, N55, N20, S55, etc.). M models and turbocharged engines typically allow higher burn rates than base models.
Parts that fix it
An oil catch can is the most popular aftermarket fix, trapping oil vapors before they enter the intake. Select the part that matches your engine family and model year.
Mishimoto Baffled Oil Catch Can - F8X M3/M4/M2 Competition by Mishimoto - $262.55. Direct fit for F80/F82/F83 M3, M4, and M2 Competition models.
Mishimoto Baffled Oil Catch Can for BMW F82 M4 by OEM - $262.55. Fits F82 M4 and compatible F80 M3 chassis with color-matched finish.
Mishimoto Baffled Oil Catch Can for BMW N20 N26 CCV Side by Mishimoto - $238.95. Designed for N20 and N26 four-cylinder engines on F30 and F32 chassis.
Mishimoto Baffled Oil Catch Can - N55 335i/135i 2011-2013 by Mishimoto - $230.95. Purpose-built for N55 turbo engines in E90 335i, E91 wagon, and E82 135i.
Mishimoto Baffled Oil Catch Can - N54 CCV Side (2007–2010) by Mishimoto - $223.95. Fits first-generation N54 twin-turbo engines on E90 335i and E82 135i models.
FTP Motorsport N55 Oil Catch Can for F2X and F3X BMWs by FTP Motorsport - $170. Compact design compatible with N55 turbo engines across F20, F30, and F34 body styles.