BMW X1 Heat Issues, Water Valve or Something Else?

Hi there! I have some experience working with cars, and I actually faced a similar issue with my 2013 BMW X3 last winter. The symptoms were nearly identical to what you're describing with your X1. Took it to my regular workshop and they diagnosed it as a faulty cable connection to the water valve control unit. The connection had corroded over time, causing intermittent heating performance. The fix was relatively straightforward, they replaced the wiring harness and connectors, cost me about 95 Euro total. Before jumping to conclusions though, could you share: What error codes you're getting? Does the issue happen right from startup or after driving for a while? Are you noticing any coolant loss? This info would help confirm if you're dealing with the same problem I had. The X series are great cars but these heating gremlins can pop up from time to time. If it's the same issue, it's a relatively quick fix.

Thanks for the detailed response! I checked the error codes, getting P0597 and P0599. The heating issues start pretty much right after startup and stays problematic throughout. Haven't noticed any coolant loss though. Just had my service done at 9700 KM last month and everything else seems fine. Based on your experience, it does sound similar to what you faced. Really hoping it's just the wiring and not the entire valve assembly that needs replacement. I'll mention your feedback when I take it to the shop tomorrow. At least I have a better idea what to expect now. Thanks again for sharing your experience, super helpful to hear from someone who's dealt with this before!

Hey, glad I could help earlier! Following up on your error codes, P0597 and P0599 actually confirm my initial suspicion about the wiring being the culprit. Those codes specifically point to thermostat heater control circuit issues, which matches perfectly with what I experienced. Just to share more from my case, my mechanic showed me the corroded wiring, and it was pretty obvious once they opened it up. The insulation had worn down near the connection point, leading to intermittent contact. Since you're not losing coolant, I'm even more confident it's the same electrical issue rather than a mechanical problem with the valve itself. Quick tip though, when you take it to the shop, ask them to check the connector housing too, not just the wires. In my case, they found some moisture had gotten in there over time, which contributed to the corrosion. Getting that replaced along with the wiring harness has prevented any issues from coming back. 95 Euro was all it took for me, and it's been working perfectly since then. Hopefully, you'll have the same straightforward fix. Let me know how it goes at the shop, always curious to hear if these similar cases end up having the same solution!

Thanks so much for the follow-up info! That's really reassuring to hear that the error codes match your experience. I just called the shop and scheduled it for tomorrow morning, and made sure to mention checking both the wiring harness and the connector housing like you suggested. The price point you mentioned seems pretty reasonable too, definitely better than what I was fearing it might cost. I was worried I'd be looking at a major repair bill, so this is a relief. I'll definitely keep you posted on what they find. Really appreciate you taking the time to share all these details, it's making me feel much more confident about handling this issue! By the way, since you seem pretty knowledgeable about BMWs, would you recommend any preventive maintenance to avoid similar issues in the future? Just wanting to stay ahead of any potential problems once this is fixed.