BMW Diesel Power Loss: DPF or Sensor to Blame?

I had similar issues with my 2015 BMW 3 Series diesel last year. The symptoms you're describing are exactly what I experienced, power loss, sluggish response, and increased fuel consumption. Turned out I had a significant vacuum leak at the intake manifold. The rubber seals had deteriorated, causing a massive air leak. The mechanic showed me that several vacuum lines were cracked, and the intake boot had a tear. They replaced all the vacuum lines, gaskets, and the intake boot. It was quite a serious issue since vacuum leaks can affect various engine components and sensors, potentially causing long-term damage if left unchecked. The repair took about 4 hours, but the car ran like new afterward. The throttle response returned, and fuel economy went back to normal. Your symptoms do sound like a vacuum leak rather than just a manifold pressure sensor, but get it diagnosed properly. Don't wait too long, these issues tend to get worse and more expensive if ignored.

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm going through. My car's behaving the same way, it's such a relief to hear you got it sorted out. Would you mind sharing how much the repair cost you? Also, has everything stayed running smoothly since the fix, or have you noticed any other issues pop up?

Hey there! Glad to help follow up on this. Yeah, I actually just got back from the shop last week about this exact issue. While my initial diagnosis was a vacuum leak (which was causing similar symptoms), they found the root cause was actually a faulty manifold pressure sensor. Got that replaced along with fixing a pretty substantial vacuum leak they discovered during inspection. The total came to 235 € for parts and labor. The car's running absolutely fantastic now, like night and day difference! The sluggishness is completely gone, and I'm getting much better fuel economy again. It's been about a week since the repair, and everything's stayed perfect, no engine lights, no power issues, nothing. The throttle response is crisp again, just like it should be. Looking back, I'm really glad I didn't wait any longer to get it fixed. These things can definitely snowball if you let them go too long. I'd say you're making the right move getting on top of it now. If you need any other info about what they did during the repair, just let me know!

Thanks so much for the detailed follow-up! Just got back from the mechanic myself actually. You were spot on, it turned out to be a combination of issues. Had both the manifold pressure sensor and some vacuum leaks fixed. The bill was a bit higher than yours at 350€, but honestly, it was worth every penny. The difference in how the car drives now is incredible! Took it for a test drive after the repair, and that sluggish feeling is completely gone. The engine's got its pep back, and I've already noticed I'm using less fuel. Best part? No more check engine light staring at me from the dashboard! Really appreciate you sharing your experience, it gave me the confidence to get it sorted quickly instead of putting it off. Feels great to have this headache behind me now. Here's hoping both our BMWs keep running smoothly!