Cayenne's Black Smoke & Stalling: Fuel Sensor Gone Bad?

Had similar issues with my 2011 Porsche Panamera last year. The symptoms you're describing match what I experienced, rough idle, black smoke, and stalling. Initially thought it was the fuel sensor too, but turned out to be a faulty wiring harness that was causing multiple misfires. Got it fixed at my local Porsche specialist after my regular mechanic couldn't properly diagnose it. The wiring harness had deteriorated over time, causing poor connections to the fuel injectors. It was actually a serious issue that needed immediate attention to prevent damage to the catalytic converter. The repair involved replacing the entire fuel injection wiring harness and connectors. Not a quick fix, but after the repair, the car ran like new, no more stalling, smooth acceleration, and the black smoke disappeared completely. Would definitely recommend going to a Porsche specialist for this one, as they have the right diagnostic tools and experience with these specific issues.

Thanks for sharing your experience! That's really helpful. I was worried it might be something more serious than just the fuel sensor, and sounds like I was right to be concerned. If you don't mind me asking, do you remember roughly how much you ended up paying for the wiring harness repair? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? I want to make sure I'm prepared for what I might be looking at cost-wise.

Hey there! Glad I could help earlier. Just wanted to follow up, I actually had my Panamera checked by the mechanic I mentioned, and it turned out my initial hunch about the wiring harness was spot on. They found and fixed the fuel level sensor malfunction, it was indeed a defective wiring harness/plug that was causing all those headaches. Only set me back 95€, which was honestly a relief considering what these repairs can sometimes cost! The car's been running like a dream since then, no more stalling, rough idle, or any of that black smoke drama. Been about a year now and no other issues have popped up. My mechanic said catching it early probably saved me from bigger problems down the road, especially with the catalytic converter. Trust me, finding a good Porsche specialist is worth its weight in gold. They might charge a bit more than your regular mechanic, but they really know what they're doing with these cars. Let me know if you need any other info!

Just wanted to update everyone who helped me out! Finally got my Cayenne fixed and what a relief! Took your advice and found a Porsche specialist nearby. You were totally right about the wiring harness, it was exactly what was causing all those problems. Ended up paying around €1,200 for the whole job, which included replacing the harness and some preventive maintenance while they were at it. More than I originally hoped to spend, but honestly, seeing how the car runs now, it was worth every cent! No more black smoke, no stalling, and it's running smooth as butter. Had to wait a couple of days for the parts to arrive, but the mechanic kept me updated throughout the whole process. Super professional and actually explained everything they were doing, such a different experience from my last mechanic! Thanks again for pointing me in the right direction. Would've probably wasted time and money going back to my regular guy. Really appreciate all the help!