Valve cover / PCVBMW
BMW Valve Cover and PCV
BMW valve-cover and PCV faults can create oil leaks, crankcase pressure problems, smoke, and misfires that sellers may describe as minor seepage.
Repair difficulty
Moyen
Estimated cost
Medium, but rises if coils, plugs, oxygen sensors, or oil-contaminated parts need replacement.
Affected models and engines
- BMW petrol engines including N20, B48, N55, B58 and related four- and six-cylinder models
Symptoms
- Burning oil smell
- Oil around the valve cover
- Whistling PCV noise
- Rough idle or smoke
Why it fails
- Plastic covers and rubber gaskets harden with heat.
- Integrated PCV diaphragms can split.
- Crankcase pressure faults can push oil past seals and create secondary leaks.
Checks before buying
- Inspect the rear and sides of the valve cover after a hot test drive.
- Listen for PCV whistling at idle.
- Check for oil smell through the vents.
- Scan fuel trims and misfire counters.
Fault codes to investigate
Fault codes guide diagnosis; they do not confirm a part without live data, inspection, service history, and repeat testing.
Related research
Continue your research
Move from brand context to exact model, powertrain, fault-code, and buying-checklist evidence.
Aide à l'acheteur
Request a used-car risk review
Envoyez-nous le modèle, l'année, le moteur et le kilométrage. Nous vous aiderons à identifier les principaux risques avant d’acheter.
Points faibles connus du moteur et de la boîte de vitesses.
Codes d'erreur et symptômes à vérifier.
Questions d'inspection avant négociation.
Il s’agit d’un guide pour l’acheteur, et non d’une inspection mécanique à distance ou d’une garantie. Vérifiez toujours la voiture en personne avec les diagnostics et les dossiers d'entretien.