Black Smoke & Power Loss in 991: Exhaust System Crisis?

I have some experience working on cars and had a similar issue with my 2014 Porsche Cayman. After taking it to my trusted mechanic, they diagnosed a faulty lambda sensor that was causing those exact symptoms, black smoke, CEL, power loss, and that nasty exhaust smell. Cost me around 375€ to get it replaced, but it fixed everything perfectly. What's your mileage and have you noticed any other symptoms? Also, have you scanned for error codes? This info would help confirm if it's the same issue I had.

Thanks for sharing your experience! My mileage is 75670 KM and just had service last month. I haven't scanned for codes yet, but I'm planning to do that tomorrow. The lambda sensor issue you mentioned sounds pretty similar to what I'm experiencing. I'll definitely get that checked out. Did you notice any rough idling before getting yours fixed? The price doesn't sound too bad considering what I was expecting to pay. Really appreciate the input!

Hey again! Yeah, now that you mention the rough idling, I definitely had that issue too with my Cayman before getting it fixed. It was especially noticeable when the engine was cold. Looking at your mileage (75670 KM), it's actually pretty close to when mine started acting up (around 70K). The lambda sensor going bad is pretty common on these models, and the symptoms match up perfectly. When I got mine scanned, it showed P0135 and P0141 codes, might be worth checking if you get similar ones. My mechanic mentioned that these sensors typically last between 60,000 to 80,000 KM, so you're right in that window. Just a heads up, make sure they check both upstream and downstream sensors while they're at it. Sometimes when one goes bad, the other isn't far behind. I actually ended up replacing both just to be safe, which bumped the total cost to about 600€, but it was worth it for the peace of mind. Let us know what the scan shows tomorrow! If it turns out to be the same issue, at least you'll know it's a relatively straightforward fix.

Thanks so much for all the detailed info! That's super helpful to know about the codes and the lifespan of these sensors. I'll definitely have them check both sensors, really don't want to deal with this issue again anytime soon. The rough idling when cold is exactly what I'm experiencing too, so I'm feeling pretty confident it's the same problem. Will update the thread tomorrow after I get those codes scanned. Fingers crossed it's just the lambda sensors and nothing more serious! Really appreciate you taking the time to share your experience, it's made me feel a lot better about the whole situation.