BMW 8's VANOS Failure Causing Power Loss & High Fuel Use

Hey there! I can relate to this. Had similar issues with my 2018 BMW M4 last year. The symptoms you're describing match exactly what I experienced, rough idle, power loss, and increased fuel consumption. In my case, it turned out to be a defective camshaft solenoid valve in the VANOS system. Initially thought it was just a sensor issue, but diagnostic tests at the service center showed it was more serious. The solenoid wasn't getting proper power supply, which messed with the valve timing. The repair involved replacing the faulty solenoid valve and cleaning the VANOS unit. It's definitely not a DIY job, requires specific diagnostic tools and expertise. The whole thing took about two days to fix, but it was worth it. Car runs like new now. Don't wait too long on this one, VANOS issues can lead to bigger engine problems if left unchecked. Would suggest finding a certified BMW specialist who knows these systems well. This is a pretty serious issue that needs proper attention.

Thanks for sharing your experience, that's really helpful to know. My situation does sound very similar to what you went through. I'm curious, do you remember roughly how much the repair ended up costing you? Also, have you had any other VANOS-related issues pop up since getting it fixed? Just trying to get an idea of what I might be looking at here for my 8.

Hey again! Happy to follow up about my M4's VANOS repair. So yeah, after getting it fixed last year, I can finally share some good news, the repair was actually pretty reasonable, came to about 250 € total. The main culprit was indeed that faulty camshaft solenoid valve I mentioned before. Once they got that sorted, the inlet VANOS started working perfectly again. And to answer your other question, nope, haven't had a single VANOS-related problem since the repair. The car's running smooth as butter now. That rough idle completely disappeared, power delivery is back to normal, and my fuel consumption dropped back to where it should be. Trust me, I know it's nerve-wracking when these issues pop up, especially with a relatively new car like your 8. But getting it fixed sooner rather than later is definitely the way to go. These VANOS problems don't typically fix themselves and can get pretty expensive if you let them develop into something bigger. One bit of advice though, make sure whoever looks at it knows their way around BMW VANOS systems. It's not rocket science, but it does need someone who knows what they're doing.

Thanks for all that detailed info! Actually, I bit the bullet and got my car checked out by a BMW specialist yesterday. You were spot on about the solenoid, that's exactly what it was. Funny enough, my repair cost was pretty close to yours, just a bit higher at 300 €. The whole experience wasn't nearly as bad as I feared. The specialist was really straightforward, explained everything clearly, and got the work done in just one day. The car's running perfectly now, that annoying rough idle is gone, and it's got its punch back when accelerating. Really glad I didn't put this off any longer. You were absolutely right about finding someone who knows BMWs well, made a huge difference compared to my last mechanic. Thanks again for pushing me in the right direction with this. Sometimes you just need that extra bit of confidence from someone who's been through the same thing.