BMW X6 Diesel Power Loss & Fuel Economy Mystery

Hey there! I went through something very similar with my 2014 BMW X5 35d last year. The symptoms match what I experienced, poor starting, increased fuel consumption, and reduced power. In my case, it turned out to be faulty fuel injectors that were causing incorrect cylinder pressure, which then led to carbon build-up in the intake manifold. The check engine light was my first warning too. Initially, I thought it was just a sensor issue, but the diagnostic revealed the injectors were the root cause. The carbon build-up was actually a secondary problem that developed because of the faulty injectors. It was quite a serious issue that needed immediate attention to prevent further engine damage. My mechanic had to replace two injectors and clean the intake manifold. The whole repair took about three days. Since then, the engine's been running like new, crisp response, normal fuel consumption, and smooth cold starts. Given your symptoms, I'd strongly suggest getting it checked soon. These issues tend to get worse and can cause more expensive problems if left unaddressed. Best of luck with the repairs.

Thank you so much for sharing your experience! That's really helpful, as it sounds exactly like what I'm dealing with. I'm relieved to hear you got it sorted out. Would you mind telling me what the total repair cost was? Also, has everything been running smoothly since the fix, or have you noticed any other issues popping up? I want to make sure I'm prepared for what I might be facing with my X6. Thanks again for your input!

Hey again! Happy to update you! After getting it fixed, my X5 has been running absolutely perfectly, it's like a different car now. The cylinder pressure issue was completely resolved after they found it was a consequential error from the injector problem. The best part? The repair for the pressure fluctuation didn't cost me anything since it was covered under the previous repair warranty. Sometimes you get lucky! It's been about a year now, and I haven't had a single problem since. Cold starts are perfect, power delivery is smooth, and fuel consumption is back to normal. My mechanic explained that catching these issues early probably saved me from more serious problems down the line. Just make sure you find someone who really knows BMWs, it makes all the difference. These engines are pretty complex, and you want someone who can spot these connected issues like they did in my case. Hope this helps give you a better idea of what you might be dealing with. Let us know how it goes with your X6!

Just wanted to update everyone on my X6 situation. Finally got it sorted out! Took it to a BMW specialist after reading all your helpful responses. Turned out it was indeed an injector issue, plus some carbon build-up, just like you mentioned. They replaced two injectors and did a thorough cleaning of the system. The total bill came to around €2,100, which wasn't cheap, but totally worth it. The car runs amazingly now, no more sluggish starts or excessive fuel consumption. The check engine light's gone too, and the power is back to what it should be. I actually learned they caught another small issue during the inspection that could've turned into a bigger problem later, so I'm really glad I didn't wait any longer to get it checked out. The mechanic explained everything clearly and even showed me the old parts. Really appreciate everyone's input, especially your detailed response about your X5 experience. It really helped me understand what I was dealing with and gave me confidence to get it sorted properly. Thanks again!