BMW XM Check Engine Light Symptoms, Owners Need Help

Had similar issues with my 2019 BMW X7 a few months back. Initially thought it was the knock sensor too, but turned out the connection cable to the mass airflow sensor was loose and damaged. The symptoms were identical, poor acceleration, high fuel consumption, and rough idle. Took it to the garage and they found corrosion on the connector pins. They had to replace the entire wiring harness for that section. Not a super expensive fix, but definitely needed professional attention as it could've led to more serious engine problems if left unchecked. For your XM, I'd recommend getting it diagnosed properly. These symptoms could be various things, from sensor issues to ignition coil problems. My case was relatively straightforward once properly diagnosed, but the symptoms can be misleading. The repair took about 4 hours at the shop. Don't wait too long, driving with these issues could cause more damage to other engine components.

Thanks for sharing your experience! It's good to know I'm not alone with these issues. Sounds like you got it sorted out pretty well with the wiring harness replacement. I'm curious though, do you remember roughly how much you ended up paying for the whole repair? And has everything been running smoothly since then, or have you noticed any other problems pop up? I'm thinking I should probably get mine checked out sooner rather than later based on what you're saying about potential engine damage. Been putting it off but you're right, probably not worth the risk.

Hey there! Just wanted to follow up about those costs you asked about. So yeah, when I took my X7 in, they found it actually was the knock sensor giving trouble, similar to what you suspected with yours. The repair bill came to 95 € to fix the cable connection that had gone bad. Pretty reasonable, if you ask me! The best part? My car's been running like a dream since then! No more sluggish acceleration, fuel consumption is back to normal, and that annoying rough idle is completely gone. Kind of kicking myself for not getting it sorted sooner, but you live and learn, right? You're definitely making the right call getting yours checked out soon. These modern BMWs are amazing machines, but when something's off, it's best to tackle it quickly. Since sorting mine out, I've had zero issues, it's back to being the smooth, powerful ride it should be. Let me know how you get on with yours. Always interested to hear if others run into similar fixes with their BMWs!

I actually bit the bullet and took my XM to the mechanic yesterday! You were spot on about dealing with it quickly. Turns out it was a faulty oxygen sensor that was causing all the trouble, not the knock sensor like I initially thought. The mechanic spotted the issue right away and had some replacement parts on hand. The whole thing cost about 300 bucks and took just a couple of hours. The best part? My car's running perfectly now! That sluggish acceleration is gone, and I'm not burning through fuel like crazy anymore. The idle is smooth as silk too. I feel pretty silly for putting it off so long, especially since the fix was relatively straightforward. The mechanic was really professional, explained everything clearly and even showed me the old sensor. Definitely keeping this shop in mind for future maintenance. Thanks again for pushing me to get it checked out. Nothing beats having the car running the way it should!