BMW Diesel Cold Start Issues, Seeking Solutions

Hey there! I've got some experience working on cars. Had a similar problem with my 2011 BMW 3 Series diesel last winter. Initially thought it was something major with the engine control unit, but turned out to be much simpler. After taking it to my regular workshop, they found loose battery cable connections were the culprit. These connections were causing poor electrical contact, especially in cold weather. Got it fixed for around 155 Euro, they cleaned the terminals, replaced some corroded connectors, and secured everything properly. Haven't had any starting issues since then. Before you head to a mechanic though, what's the exact behavior when you try to start it? Does it crank at all? Any warning lights on the dash? Also, have you noticed any other electrical issues lately? These details would help determine if you're facing the same problem. Definitely worth checking the battery connections first, it's often the simple things that cause the biggest headaches!

Hey, thanks for sharing your experience! My car has about 40213 KM on it and had its last service just 2 months ago. What you're describing sounds very similar to what I'm experiencing, when I try to start it, the engine cranks but seems to struggle, especially on cold mornings. No warning lights showing up though, which is interesting. I'll definitely check those battery connections first before diving into anything more complex. Did your mechanic mention how to spot if the connectors are starting to corrode? Would love to know what signs to look for.

Hey again! Yeah, from what you're describing, it really does sound similar to what I dealt with. Since you mentioned your car has around 40K on it, it's about the same mileage where I started having these issues with my BMW. Even with recent servicing, these connection problems can pop up, especially if they weren't specifically checked during the service. About spotting corrosion, my mechanic showed me what to look for. The main signs are a greenish or whitish crusty buildup around the battery terminals and connectors. In my case, they weren't obviously corroded, but there was this slight whitish film that I hadn't noticed before. Also, if you gently wiggle the cables (with the car off, of course), they shouldn't move at all. Mine had a tiny bit of play, which turned out to be part of the problem. Quick tip from my experience, before heading to the mechanic, you can try cleaning the battery terminals with a wire brush if you have one. That's actually what I tried first, and while it helped temporarily, I still needed the professional fix for the connectors themselves. Just be careful if you try this yourself, always disconnect the negative terminal first. Let me know how it goes if you check those connections. Would be interesting to see if you're dealing with the same issue I had!

Thanks so much for the detailed advice! I just went out to check the battery connections like you suggested, and you won't believe it, I actually found that whitish film you mentioned on one of the terminals! Guess I never really paid attention to it before. I'm feeling a bit more confident now that we might be onto something here. I think I'll try cleaning those terminals first with a wire brush like you mentioned. Really appreciate the safety tip about disconnecting the negative terminal first, definitely wouldn't have known that! If that doesn't completely solve it, I'll get it to a mechanic to check those connectors properly. It's such a relief to know this might not be some major engine control issue after all. Will keep you posted on how it goes after I try cleaning those connections. Really grateful for you taking the time to share your experience, saved me from panicking about potentially expensive repairs!