Mercedes SL Engine Issues Resolved

The symptoms you describe—check engine light, power loss, and smoke—strongly suggest a crankcase ventilation problem, specifically a defective PCV valve. It is imperative that you address this promptly, as a malfunctioning PCV valve can lead to increased oil consumption, compromised engine performance, and elevated emissions. I encountered similar difficulties with my SL. Was the idle also rough or erratic? Because that too, can be a key indicator.

Thanks for the quick response! Yes, now that you mention it, the idle does seem a bit rougher than usual. What exactly did you do to fix yours? Did you replace the PCV valve yourself, or did you take it to a mechanic? Also, about how much did the malfunction end up costing to fix?

Given the confluence of symptoms—rough idle, smoke, power loss, and the check engine light—coupled with the inherent complexity of modern engine management systems, I must strongly advise against undertaking repairs without proper diagnostic equipment and expertise. In my situation, a complete diagnostic assessment confirmed the PCV valve malfunction and revealed consequential issues stemming from the extended period of operation with said malfunction. The prudent course of action is to entrust the diagnosis and repair to a qualified technician. I suggest you prepare for an expense in the neighborhood of 360€ for the PCV valve replacement and associated maintenance.

Thanks for the advice! I took it to a trusted mechanic and you were spot on. It was indeed the PCV valve and the total cost was almost exactly what you predicted. Everything is running smoothly now.