BMW 1 Series Diesel: Cold Start & Power Issues Need Help

Hey there! I've got some experience working on BMWs since I drive a 2011 3 Series diesel. Had a pretty similar issue with my 320d last winter. While I have decent DIY experience, I wanted a pro to look at it since these symptoms can be tricky. Took it to my regular workshop and turns out it was just a loose connection at the fuel heater plug. The wiring had worked itself loose over time, causing those exact symptoms, rough cold starts, power drops, higher fuel consumption. Total fix was 95 Euro for diagnostics and fixing the connection. They had it done in about an hour. Could you share some more details about your 1 Series? Like the specific engine code and whether you've had any other warning lights? Also, when did you last change your fuel filter? These details would help confirm if we're dealing with the same issue.

Thanks for sharing your experience! Mine's got 23142 KM on the clock and just had its service last month where they changed the oil and filters. That loose connection issue sounds similar to what I'm experiencing. No other warning lights except the check engine, and the symptoms started about two weeks ago. I'll definitely get the wiring checked out first before replacing any parts. Good to know it might be a simple fix rather than something major.

Hey again! Yeah, since you mentioned the recent service and similar symptoms, I'm even more convinced it's probably that loose connection like I had. One thing I forgot to mention about my experience, after they fixed the connection, I had them add some dielectric grease to prevent future corrosion and keep the connection secure. It's been over a year now, and I haven't had any issues since. Given that your symptoms started after the service, there's a decent chance they might have accidentally knocked the connector loose while working on something else. It happens pretty often with these BMWs, there's a lot packed into that engine bay! Quick tip though, if you're taking it to the shop, ask them to check the connector's condition too, not just the connection itself. On my 320d, they noticed the plastic was slightly cracked, which could've caused problems down the line. They reinforced it with some heat-shrink tubing as a preventive measure. Let me know how it goes! Always good to compare notes with other BMW diesel owners.

Thanks for all that detailed info! Just got back from the mechanic and you were spot on, it was exactly what you described. The connector had worked loose during the service, and they found a hairline crack in the plastic housing too. Fixed both issues, added that dielectric grease you mentioned, and even used the heat-shrink tubing trick. Car's running like new again! Cold starts are smooth, power's back to normal, and fuel consumption has dropped back to what it should be. Total bill came to about the same as yours, mostly for diagnostic time. Really glad I asked here before jumping to conclusions about needing major repairs. Really appreciate you taking the time to share your experience, saved me from potentially replacing parts that weren't actually faulty. These BMWs might be complicated, but at least we've got a good community to help figure things out!