BMW 1 Series Rough Idle & Vibration Diagnosis Needed

Hi there! I had very similar issues with my 2012 BMW 3 Series diesel at around 155K km. Initially thought it was engine mounts too, but turned out to be a faulty glow plug and wiring harness connection. The symptoms matched yours exactly, rough idle, excessive vibration, and the check engine light. Took it to the garage last month, and they diagnosed it properly with their diagnostic system. They had to replace two glow plugs and fix a corroded wiring connection. It wasn't a major repair in terms of engine damage, but it definitely needed immediate attention to prevent further issues. The mechanic showed me the old parts, the corrosion had really done a number on the connections. Main thing is finding a shop that specializes in German cars and has the right diagnostic tools. Ask if they have BMW-specific scanning equipment before you commit. Since you're dealing with a diesel, you want someone who really knows these engines.

Hey, glad you shared your experience! That's pretty helpful since I'm currently dealing with similar symptoms. I actually took it in yesterday and you were spot on, it was indeed the glow plugs causing all that trouble. Quick question though, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? Trying to figure out if I should keep an eye out for anything specific.

Hey again! Just saw your follow-up, glad you got it checked out! Actually, when I took mine in, they found it was a mix of issues. While the glow plugs were acting up, there was also that engine mount problem I mentioned earlier. Got both fixed in one go. The cable/plug connection work set me back 95€, which wasn't too bad considering what I was worried it might cost! Since getting it sorted, my 3 Series has been running like a dream, no more weird vibrations or rough idling. It's amazing what a difference fixing that engine mount made. The engine's now sitting properly and everything's super smooth. Been about a month now and no other issues have popped up. One tip though, keep an ear out for any unusual noises, especially during cold starts. These BMWs can be a bit finicky in that department, but when they're running right, they're fantastic cars. Just make sure you stay on top of the regular maintenance and you should be good to go!

Thanks for the detailed response! Just got back from the mechanic today and wanted to share my experience. Turned out my issue was indeed similar but had an interesting twist. The glow plugs were shot, but they also found a cracked vacuum hose that was contributing to the rough idle. The mechanic was actually great, super transparent and showed me all the worn parts. Total bill came to around 300 for parts and labor, which wasn't as bad as I feared. They even did a general inspection and gave me a heads up about some preventive maintenance I might want to consider in the next few months. Car's running much smoother now, feels like a completely different vehicle! The vibration is gone and the idle is perfect. Really glad I didn't put this off any longer. Guess sometimes you just need to bite the bullet and find a new mechanic when the old one isn't cutting it. Thanks again for sharing your experience, it gave me the push I needed to get this sorted out properly!