BMW X4 Diesel Glow Plug Nightmare: Fix & Costs Guide

Hey there! I had similar issues with my 2016 BMW X3 30d last winter. Based on your symptoms, it's definitely pointing towards the glow plug system, I dealt with exactly this. The black smoke and cold start problems are classic signs. In my case, the preheat control unit connector had corroded, and two glow plugs were completely shot. The harness also showed signs of wear. It was a serious issue since it was affecting the entire combustion process and could've damaged other components if left unfixed. My trusted mechanic diagnosed it properly, they found the faulty connection was causing irregular voltage to the glow plugs, which explained the constant warning light. The repair involved replacing the control unit, all glow plugs (since they were deteriorated), and the wiring harness. I'd suggest getting it checked soon, these symptoms won't resolve themselves and could lead to bigger problems with your turbo and DPF. The repair took about a day at the shop. Hope this helps.

Thanks for sharing your experience. It sounds exactly like what I'm dealing with, and it's good to know I'm not the only one who's faced this. Just wondering, do you remember roughly how much you ended up paying for the whole repair job? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? Would be great to know what to expect moving forward.

Hey again! Good news, I just got mine fixed last week actually! After seeing your post, I decided to take my X3 to a different mechanic since it sounded so similar. Turned out the preheating control unit was definitely the culprit, just like I suspected in my first reply. The repair was way simpler (and cheaper!) than I initially thought. They found it was just a faulty cable connection to the control unit, total bill came to 95 € for the fix. Much better than what I was expecting when they first diagnosed my car. And I'm happy to report everything's running like a dream now! No more black smoke, cold starts are perfect, and that annoying glow plug light has finally disappeared. The engine feels much smoother during acceleration too. Honestly wish I'd gotten it sorted sooner instead of worrying about it for so long. Just make sure you get someone who knows what they're doing, a proper diagnosis makes all the difference. Better to fix it now before it causes any problems with your turbo or DPF. Let me know how you get on with yours!

Thanks so much for the follow-up! You've actually motivated me to get this sorted. I finally took my X4 to a new mechanic yesterday, a specialist who came highly recommended. What a difference from my last experience! Funny enough, my issue was a bit more complex than yours. They found two failed glow plugs and a damaged control unit. The whole repair took about four hours and cost me more than yours, but at least it's finally fixed. No more black smoke, and the car starts perfectly now, even in cold weather. Really appreciate everyone's help on this. It's such a relief to have it sorted, and I definitely learned my lesson about not waiting too long when these warning signs pop up. The mechanic even showed me what to watch out for in the future, which was super helpful. Thanks again for sharing your experience, it really helped me make the decision to get it fixed properly!