S90 high fuel consumption stalling black smoke

That sounds familiar! I had almost the exact same symptoms with my S90 a while back. Check engine light, rough idling, and the fuel economy tanked. How's the air intake looking? When was the last time you cleaned or replaced the air filter? That could contribute to the MAF sensor getting dirty and giving bad readings. Is the smoke black or more of a greyish color?

The air filter is pretty new, changed it like 5,000 km ago. The smoke is more on the black side, I would say. Did you also have black smoke? What was the fix in your case? I'm trying to avoid a huge repair bill if I can, but this is driving me nuts!

Yep, black smoke was part of the fun! It definitely sounds like the MAF sensor to me. Honestly, I tried cleaning it, but it was a temporary fix at best. Eventually, I had to bite the bullet and replace the sensor. I'd recommend taking it to a trusted mechanic to confirm, but be prepared for a new MAF sensor. It ended up costing me around 365€ including labor.

Thanks a lot for the info! I was hoping it wouldn't come to that, but it sounds like the MAF sensor is the culprit. I'll take it to the shop and get it checked out. At least now I have an idea of what to expect. Really appreciate your help!