BMW 1 Temp Sensor Chaos: Multiple System Failures

Hi there! I have some experience working on BMWs and went through something very similar with my 2011 BMW 3 Series diesel (coming from a previous 5 Series). Had almost identical symptoms, climate control issues, dead temp display, and frozen nozzles. Turned out to be a loose connection at the temp sensor plug. My workshop traced it down and found corrosion had damaged the wiring harness connection. They cleaned the contacts and replaced the damaged cable section. Total bill was 95 Euro and it fixed everything. Been working perfectly for over a year now. Which engine variant is your 1 Series running? Would help to know that plus whether you've noticed any other electrical gremlins. Also, did these issues start gradually or all at once? Let me know and I might be able to share more specific advice from my experience.

Thanks for sharing your experience! I've got the diesel variant that's showing 63076 KM on the clock. Actually, these problems showed up pretty suddenly after my last service. The symptoms in my case are exactly what you described, it's pretty annoying, especially with the climate control acting up. Really appreciate the insight about the corroded wiring harness, that sounds like it could be my issue too. I'll definitely get the workshop to check the sensor connections. The price you mentioned for the fix sounds reasonable, beats having to replace the entire system! Did you notice any warning lights on the dash before the problems started?

Hey again! Yeah, I remember dealing with this on my BMW, good to hear back from you. About warning lights, actually no, I didn't see any before everything went haywire. That's what made it so tricky to diagnose at first. Since you mentioned it started after your last service, that rings a bell. My issues popped up after they did some work in the engine bay too. Turns out they might've accidentally disturbed the wiring while working on something else. These sensors are pretty sensitive to any movement or moisture getting in. One thing I forgot to mention in my first reply, before taking it to the workshop, I tried disconnecting my battery for about 15 minutes to reset the system. Didn't solve the problem but might be worth trying since it's free and easy to do. Seeing as your mileage is similar to what mine was when this happened (I was around 68000 KM), it's probably the same issue. Just make sure they thoroughly check all the connections, not just the sensor itself. My mechanic found that the insulation had worn off slightly where the wiring bent around a bracket, causing intermittent problems. Let us know how it goes when you get it checked out!

Thanks for all that extra detail! The battery reset tip is really helpful, I'll definitely try that before taking it to the shop. Really interesting that yours acted up after service work too. Makes me think they might've knocked something loose while working on it. The worn insulation near the bracket is exactly the kind of specific info I was hoping to learn about. I'll disconnect the battery tonight and see what happens. If that doesn't work, I'll get it booked in and make sure to mention checking the wiring harness and connections, especially around those bracket areas you mentioned. The fact that your fix has lasted over a year is really encouraging. Really appreciate you taking the time to share your experience. I'll get back to this thread once I know what the actual problem was, might help someone else with similar issues down the line!