BMW M3 Multiple Sensor Failures, Common Rain Sensor Issue?

Hey there! I have some experience working on cars and had a similar issue with my 2008 BMW 335i (though I also own a 330i). The symptoms you're describing sound very familiar. In my case, it turned out to be bubbles forming under the gel pad of the windshield where the rain-light sensor sits. This caused all sorts of wonky behavior with multiple systems. I took it to my regular workshop and they confirmed the sensor wasn't making proper contact due to the deteriorating gel pad. The fix was pretty straightforward, they replaced the gel pad and recalibrated the sensor. Cost me about 62 Euro and everything went back to normal. Before you start replacing parts, could you share: Have you noticed any visible damage or bubbling around the sensor area? What error codes are you getting exactly? Did these issues start gradually or all at once? This might help narrow down if you're dealing with the same problem I had or if it's something else entirely.

Thanks for the detailed response! My M3 has only 20205 KM and had its last service 2 months ago. The issues actually started right after a really hot day when I noticed bubbling around the sensor area, pretty much like what you described. Will definitely check the gel pad first before jumping to replace the whole sensor. Thanks for saving me some potential unnecessary expenses! Let me see what my mechanic says about this.

Hey again! Really glad I could help with my previous response. That low mileage on your M3 actually makes perfect sense with the gel pad issue, it's more about age and heat exposure than miles driven. I had almost the exact same scenario with my 335i during last summer's heat wave. Just wanted to add, since you mentioned the timing of the issues starting after a hot day, that's exactly what triggered mine too. The heat basically accelerated the deterioration of the gel pad. When I took my car in, my mechanic showed me how the old pad had practically separated from the glass in some spots. Quick tip from my experience, while they're replacing the gel pad, have them check the sensor's electrical connections too. Mine had a bit of corrosion that they cleaned up, and it made a noticeable difference in how responsive the auto features became. Really happy you're getting it checked out before replacing the whole sensor. Looking forward to hearing how it turns out. Let me know if you need any other info about what they did with mine!

Thanks so much for the extra tips! You've been super helpful. I just called my mechanic and scheduled an appointment for tomorrow morning. Mentioned the gel pad issue and he agreed it's likely the culprit, especially given the timing with the hot weather. Really appreciate the heads-up about checking the electrical connections too, I'll make sure to ask him to look at those while he's at it. It's such a relief knowing someone else went through the same thing and got it sorted without major expense. I'll definitely update you once it's fixed. Maybe this info will help other BMW owners dealing with similar issues. Thanks again for taking the time to share your experience, you've saved me from unnecessarily replacing the whole sensor unit!