Peugeot 607 mass air flow sensor failure

Sounds like a classic mass air flow sensor issue. I had similar symptoms on my old car when the air-fuel ratio went bonkers. Is your air intake clean? A dirty air filter can mess with the sensor readings and might trigger the check engine light too. When was the last time you changed it?

Hmm, I did check the air filter a while ago and it seemed okay. But now that you mention it, maybe I should replace it just to be sure. But if it is the mass air flow sensor, is that something I can fix myself, or am I looking at a mechanic visit?

Replacing the air filter is a cheap start, but with all those symptoms, especially the stalling and smoke, it really does point towards a defective mass air flow sensor. I wouldn't risk messing with the sensor yourself unless you're really confident. Best take it to a workshop; they can diagnose it properly and replace the sensor if needed. Sensor failure can cause a bunch of issues.

Thanks a bunch for the advice! I kinda figured it was beyond my skills. Just got back from the shop. You nailed it! Mass air flow sensor was indeed toast. Cost me 365€ to get it fixed. Runs like new now, no more smoke!