BMW 6 Rough Idle & Stalling, IAC Valve Issue?

Hey there! I had a very similar issue with my 2003 BMW 5 Series last year. The symptoms you're describing sound exactly like what I experienced, rough idle, stalling, and that dreaded check engine light. Took it to my trusted workshop, and it turned out the intake was severely contaminated, which was messing with the airflow. They had to do a thorough intake cleaning service. Set me back about 425 Euro, but the car's been running smooth as silk since then. Before you head to the shop, could you share: What's your current mileage? Have you noticed any loss in power while driving? Any unusual sounds when accelerating? These details would help to confirm if we're dealing with the same issue. I'm pretty familiar with the 6 Series too (my owns a 645i), so happy to share more specific insights once I know more about your situation.

Thanks for your detailed response! My BMW's at 66759 KM and just had its service last month. Yeah, I've definitely noticed some power loss, especially when accelerating from a stop. No weird sounds though, just the irregular idle that's driving me nuts. Your intake cleaning suggestion sounds promising, definitely cheaper than replacing the idle control valve I was worried about. It's good to hear you got yours sorted without any major parts replacement. I'll mention this to my mechanic and have them check the intake first. Really appreciate the help! These older BMWs can be tricky sometimes, but they're worth the occasional headache.

Hey again! Thanks for the follow-up. Funny enough, my symptoms started right around that mileage too, I was at about 70K when it all began. Looking at your description of the power loss from a stop, that's practically identical to what I dealt with. My mechanic actually showed me the gunk build-up in the intake when they were working on it, you wouldn't believe how much crud can accumulate in there over time! Quick tip from my experience: after the cleaning, I started using a higher-grade fuel and a fuel system cleaner every few months. Been running like a dream for over a year now. The BMW engines are pretty sensitive to carbon build-up, especially these older models. Just keep an eye on it after the cleaning, if you're still getting those symptoms, then yeah, might need to look at the idle control valve. But honestly, based on what you're describing, I'd put money on it being the dirty intake. My car was like a different machine after the cleaning, no more stalling, smooth idle, proper power delivery. Let me know how it goes after you get it checked out. Always good to compare notes with another BMW owner!

Thanks so much for all that insight! You're totally right about these engines being sensitive. I'll definitely try that tip about the higher-grade fuel and system cleaner after getting it fixed, sounds like good preventive maintenance. Just booked it in at the shop for tomorrow morning. I'm feeling much more confident now going in with this information. At least I won't feel completely lost when talking to the mechanic about the possible intake issues. Really hoping it's just a cleaning job like yours was. Will update once I get the verdict. It's great having someone who's been through the same thing, makes dealing with these car issues way less stressful. Thanks again for taking the time to share your experience!