BMW Diesel Glow Plug Warning Signs: What It May Cost

I had nearly identical issues with my 2018 BMW 5 Series diesel. The symptoms you're describing match exactly what I experienced, persistent glow plug light, rough cold starts, and that telltale smoke under acceleration. Last month at the garage, they diagnosed a faulty connection between the glow plug control module and the plugs themselves. The wiring harness had degraded, causing intermittent connectivity issues. In my case, two of the glow plugs also needed replacement since they'd burned out from the electrical irregularities. While the diagnosis took some time with component testing, the actual fix wasn't too complex. The mechanic installed a new wiring harness and replaced the affected glow plugs. Not a catastrophic issue, but definitely one that needs addressing soon to prevent potential engine damage. For reference, the whole job took about 4 hours to complete. I'd recommend getting it checked soon, especially with winter approaching. These symptoms typically don't resolve themselves and can worsen over time.

Thanks so much for sharing your experience, it's really helpful to know I'm not alone with this issue! The wiring harness problem makes total sense given the symptoms. Would you mind telling me how much you ended up paying for everything? Just trying to get a rough idea of what to expect. Also curious if you've had any other problems pop up since getting it fixed?

Hey there! Happy to give you an update. After taking it to my mechanic, it turned out to be exactly what we suspected, the Glow control unit was acting up. The fix was actually pretty straightforward and much cheaper than I initially feared. They found a dodgy cable connection to the control unit and sorted it out for just 95 €. Since getting it fixed, the car's been running like a dream! No more glow plug light staying on, cold starts are smooth again, and that annoying smoke under acceleration is completely gone. Haven't had a single issue pop up since the repair, which was about two months ago now. Honestly, I'm just relieved it wasn't anything more serious. These BMW diesels are generally solid, but when electrical gremlins show up, it can be a bit nerve-wracking until you get to the bottom of it. Hope this helps with your decision-making! Let me know if you need any other info.

I decided to take your advice and got my BMW checked out. What a relief, turned out to be a similar electrical issue! My mechanic found problems with the wiring and control unit too. Got it all sorted last week for around €600, which included labor and parts. They had to replace two glow plugs as well since they were pretty worn out. The whole experience was actually way better than my first mechanic visit. These guys knew exactly what they were looking for after I described the symptoms. They had my car running perfectly in just a few hours. Now my cold starts are smooth again, no more warning lights, and that annoying smoke is completely gone. Should've done this weeks ago instead of worrying about it! Really appreciate everyone's help here. It's always good to hear from others who've dealt with similar issues. Makes the whole process much less stressful when you know what you're dealing with. Let me know if anyone else runs into this problem, happy to share more details about my experience!