BMW i8 Hybrid Overheating with Dead Heater, Need Help!

Hey there! I can relate to your situation. I have a 2017 BMW i3s Hybrid and had similar issues last month. The overheating and heater malfunction turned out to be related to a failed water pump, which actually occurred because of a damaged thermostat that wasn't caught in time. Initially, I thought it was just the bypass valve too, but my mechanic found that the thermostat failure had caused the water pump to work overtime, eventually leading to its breakdown. It was quite serious since continuous driving could have caused engine damage. The repair required replacing both components to properly fix the issue. My suggestion would be to get it checked soon, those symptoms in hybrid systems usually indicate cooling system problems that can escalate quickly. Definitely go to someone who specializes in BMW hybrids. These issues aren't something you want to leave unattended, especially with that mileage. Best of luck with the repairs.

Thanks for sharing your experience! That's really helpful information about the thermostat and water pump connection, definitely seems similar to what I'm dealing with. Would you mind telling me roughly how much you ended up paying for the full repair? Also curious if you've had any other issues pop up since getting it fixed? Really want to get a sense of what I might be in for with this repair.

Hey again! Great to hear back from you! So here's the update on my i3s situation, actually got really lucky with the repair costs. Turned out my car was still under extended warranty, so I didn't have to pay anything for fixing that bypass valve issue. The mechanic discovered it was actually a consequential fault from that thermostat problem I mentioned before. Since getting it fixed last month, everything's been running perfectly smooth, no more overheating, heater works like a charm, and those error codes are completely gone. The engine's purring like new again. Honestly, such a relief! For your case, I'd still recommend getting it checked out ASAP by a hybrid specialist. Even though mine was covered by warranty, these cooling system issues can get pretty serious if left unchecked. Always better to catch these things early, you know? Let me know how it goes with yours, really interested to hear what they find!

Thanks so much for all this info! Just got back from the mechanic actually. You won't believe it, took your advice and went to a hybrid specialist. Turns out it was exactly what happened with yours, faulty thermostat that messed up the water pump. Had to shell out quite a bit since my warranty expired last year, but at least it's fixed right. The mechanic was super professional, showed me all the damaged parts and explained everything. Really different from my last experience! Took them about a day and a half to get everything sorted. Car's running perfectly now, no more overheating, heater's working great, and those annoying error codes are gone. Really glad I asked here and got your advice instead of going back to my old mechanic. Sometimes paying a bit more for someone who knows what they're doing is totally worth it. Thanks again for helping me dodge what could've been a much bigger problem!