Sprinter diesel check engine light and smoke

Oh man, that sounds rough! A check engine light plus smoke is never a good combo. Is the smoke black, blue, or white? That might give you a clue. Have you noticed any whistling sounds, or maybe a rough idle? I'm just throwing ideas out there, but it could be something else entirely. I had a similar thing happen on my old van, and it turned out to be a bad sensor. But PCV valve malfunction could certainly be the culprit. I'm no expert, but I'd definitely get it checked out soon.

Smoke is black. No whistling or rough idle. What else could cause black smoke besides the valve?

Okay, black smoke usually means too much fuel, not enough air, or both. A faulty PCV valve can mess with your air/fuel mixture, so it's still a strong possibility. But, honestly, black smoke can also be from a clogged air filter, bad injectors, or even turbo issues. Since you're already suspecting the crankcase ventilation, it's probably best to have a mechanic take a look. They can run some diagnostics and pinpoint the exact problem. It's tricky diagnosing these things remotely. Best not to start replacing parts randomly. Don't want to waste money!

Thanks. Mechanic confirmed the crankcase ventilation valve was defective. Repair cost 360€. Replaced the valve and the malfunction is gone.