BMW 3 Diesel Cold Start & Power Issues, Need Help!

Hi there! I have some experience working on cars and faced something very similar with my 2013 BMW 5 Series diesel. The symptoms you're describing sound exactly like what I went through. Turned out the issue was connected to a previous repair where they replaced my fuel injectors but didn't properly reset the ECU. This caused those exact symptoms, rough cold starts, excessive fuel consumption, and power loss. Took it back to the workshop, and since it was their mistake, they fixed it at no cost by properly programming the system. For better insight, could you share: How many miles/kilometers on your car? Any recent repairs or maintenance? Any other warning lights besides the check engine light? I also owned a BMW 1 Series before this, so I'm quite familiar with these engines. Happy to help troubleshoot further!

Thanks for the detailed response! My car has 10781 KM on the clock, and the last service was done about 3 months ago, just routine maintenance where they changed the oil and filters. Besides the check engine light, no other warning lights are showing up at the moment. That's interesting about the ECU reset issue. Since my car's been serviced recently, I wonder if I might be dealing with something similar. Did your car also feel particularly sluggish during acceleration when you had this problem?

Hey again! Yes, absolutely, my 5 Series had the exact same sluggish acceleration issue you're describing. It was really frustrating, especially when trying to merge onto highways. Given what you've shared about the recent maintenance and the relatively low mileage on your car, I'm even more convinced we had the same problem. In my case, the sluggishness was most noticeable when the engine was cold, and it would improve slightly after warming up. But it never felt quite right until they fixed the ECU programming. The fuel consumption was also ridiculous, I was filling up way more often than usual. Since you've had recent maintenance work done, I'd recommend taking it back to the same shop and having them check the ECU settings. They might have missed resetting something after the service. If they push back, you could mention my experience, sometimes these BMWs need specific programming after even routine maintenance. Just to add, before I got mine fixed, I actually tried running some higher-grade fuel thinking it might help, but it made zero difference. The ECU programming was the real culprit. Let me know how it goes after you get it checked out!

Thanks so much for sharing your experience! It's really helpful to know that you had similar issues with your 5 Series. You've pretty much described exactly what I'm experiencing, the cold start sluggishness and the crazy fuel consumption. I'll definitely get in touch with my service center tomorrow and ask them specifically about the ECU programming. I've actually been using premium fuel too, thinking it might help, but like you said, it hasn't made any difference. It's quite a relief to hear this might be something relatively straightforward to fix rather than a major mechanical problem. I was worried I'd be looking at some expensive repairs! I'll make sure to mention the ECU reset when I take it in. Really appreciate you taking the time to help me out with this. It's given me a much clearer direction on what to look into. I'll let you know how it goes after I get it checked out!