BMW 4 Series Heating Failure: Valve or Something Else?

Hey there! I feel your pain, had a similar issue with my 2011 BMW 3 Series last winter. The symptoms were pretty much identical to what you're describing. After taking it to the garage, turned out it wasn't the water valve but rather a loose connection in the HVAC control module wiring. The connector had corroded over time and wasn't making proper contact. The fix wasn't too complicated, but finding the actual problem took some diagnostic work. The mechanic had to trace the wiring and test several connections before locating the faulty one. They ended up replacing the connector and cleaning the contact points. Wasn't a serious repair in terms of mechanical work, but definitely something that needed fixing before it could cause more issues with the climate control system. Just a heads up, with these symptoms, it's worth having them check the entire HVAC control system rather than just assuming it's the water valve. Could save you some time and hassle in the long run.

Thanks for sharing that info about your BMW! That's really helpful to know about the HVAC control module wiring. Do you remember roughly how much you ended up paying for the diagnostic work and repair? Also, has everything been working smoothly since they fixed it, or have you noticed any other heating quirks?

Hey again! Actually, after my last post, I did end up having to take the car back to the mechanic, turned out my initial wiring issue was masking a faulty water valve too! Funny enough, your gut feeling was spot on. Got both problems sorted now though, the cable connection issue cost me 95€ to fix, which wasn't too bad considering all the diagnostic work they had to do. Since getting both issues fixed, the heating's been working perfectly, nice and even heat distribution across all zones, no more cold spots or temperature fluctuations. It's been such a relief, especially since these heating problems can be really tricky to diagnose correctly the first time around. The mechanic also mentioned it's pretty common for BMWs from our generation to have these kinds of issues crop up around the mileage you're at. I'd definitely recommend getting it checked out soon, these problems tend to get worse if you leave them too long. At least now you know to have them check both the water valve and the wiring connections!

Thanks so much for sharing all that detail about your experience! I took my car to the mechanic yesterday and you were absolutely right. They found both issues, a loose connection and a failing water valve. The diagnostic process took a couple hours, but they identified everything. Total bill came to about €350 including parts and labor. Had to wait around in their waiting room for a while, but at least they had decent coffee! The best part is, I drove home with perfect heating, first time in weeks I've been properly warm in my car. All zones are working great now, temperature is steady, and that annoying fault code is gone. Really glad I asked here first and knew what to tell them to check. Saved me from another frustrating mechanic experience! Thanks again for steering me in the right direction with this.