BMW Z4 Temperature Issues, Cooling Grille Problems?

Hey there! I have some experience working on BMWs and had a similar issue with my 2014 BMW M4 (also dealt with a few issues on my 320i). That temp gauge behavior sounds very familiar. Initially thought it was something major, but turned out to be just a faulty fuse in the cooling system control module. My mechanic spotted it during a diagnostic check. The repair was straightforward, just needed a fuse replacement, cost me 52 Euro. Before jumping to conclusions about the grille, could you share: Does the fan seem to be running normally? Any coolant leaks you've noticed? When exactly does the CEL come on? This info would help narrow things down. Could be something simple like in my case, or might need a deeper look. Let me know!

Latest service was just 2 weeks ago at 159797 KM, and I'm facing similar symptoms. Fan seems to run fine, no visible coolant leaks that I can spot. The CEL usually comes on after about 10-15 minutes of driving, especially when the engine's still trying to reach normal operating temp. I noticed the temp readings start fluctuating right around the same time. Really appreciate your input about the fuse, definitely gives me something specific to check. Mind sharing which fuse exactly was the culprit in your case?

Hey again! Thanks for those details, they're really helpful. On my M4, it was fuse F70 in the main fuse box that was causing all the drama. It's one of those 20-amp fuses that controls the engine cooling system. You know what's interesting, your symptoms are almost identical to what I experienced. My car also started acting up around the 155,000 KM mark, even though I'd just had it serviced. The timing of your CEL coming on (10-15 mins into driving) is exactly what happened with mine too. The fluctuating temp readings were driving me nuts before I figured it out. I actually ended up wasting time checking the thermostat and water pump before my mechanic pointed out the fuse issue. Should've checked that first! Since your symptoms match mine so closely, I'd definitely recommend checking that fuse before diving into more complex fixes. If you're comfortable doing it yourself, it's a pretty straightforward check. If not, any decent mechanic should be able to verify it quickly. Just keep in mind, even though the fuse fixed my issue, these BMWs can be tricky. If the fuse check doesn't solve it, might be worth having the cooling system pressure tested just to be safe.

Thanks so much for the detailed info about fuse F70! That's exactly the kind of specific advice I was hoping for. Really helpful to know it's a 20-amp fuse too. I'm actually feeling pretty relieved that this might be something relatively simple and inexpensive to fix, especially since our symptoms match up so well. I'm decent with basic car maintenance, so I'll definitely check that fuse first thing tomorrow. Was getting worried it might be something major like a water pump or thermostat failure, which would've been a much bigger hit to my wallet. You probably saved me from going down that same expensive rabbit hole you did! If it turns out to be something else, I'll take your advice about the pressure test. Really appreciate you taking the time to share your experience. Will definitely update once I get it sorted out!