BMW 3 Hybrid Radiator Fan Failure: Help Needed

Had a similar issue with my 2020 BMW 5 Series Hybrid last winter. The main culprit turned out to be a defective speed sensor that wasn't properly communicating with the cooling system. The radiator fan wasn't engaging because it wasn't getting the right signals. Initially thought it was just the fan, but my mechanic found that the speed sensor was causing the whole cooling system to malfunction. It was triggering false readings, which explains why your check engine light is on too. The repair involved replacing the sensor unit and recalibrating the cooling system control module. This isn't a minor issue, if left unchecked, it could lead to serious engine damage. My car was back to normal after the repair, and the cooling system has been working perfectly since then. Make sure whoever works on it has experience with BMW hybrid systems, the cooling setup is quite different from conventional engines.

Thanks for sharing your experience! This is really helpful as it sounds exactly like what I'm dealing with. Just to be on the safe side, do you remember roughly how much you ended up paying for the whole repair? Also, have you had any cooling-related issues pop up since getting it fixed? Trying to get an idea of what I'm in for, both cost-wise and whether this might be part of a bigger problem.

Hey there! Happy to give you the full update. After getting it fixed, I paid exactly 250€ for the speed sensor replacement, and I can tell you it was totally worth it. The radiator fan issue completely cleared up once they sorted out that faulty sensor. I've put quite a few miles on the car since then, and I'm glad to report I haven't had a single cooling problem pop up. The engine temperature stays exactly where it should be, and everything's running smooth as silk. The fan kicks in right when it needs to now, it's like having a completely different car! I was worried at first that it might be part of a bigger issue, but nope, replacing that speed sensor really did solve the whole thing. Just make sure whoever works on it knows their way around BMW hybrid systems. When they know what they're doing, it's usually a straightforward fix. Take my word for it, don't put this repair off. It's better to get it sorted now than risk any engine damage down the line.

Just got back from the mechanic, and wow, what a relief! Finally found a really good hybrid specialist who knew exactly what they were doing. Like your case, it turned out to be the speed sensor messing with the cooling system. They replaced it and did a full diagnostic check just to be thorough. The whole thing set me back about 300 bucks, which honestly isn't as bad as I was fearing. They did warn me that if I'd waited longer, it could've caused some serious damage to the engine. Been driving it for a few days now, and what a difference! The fan's working perfectly, no more check engine light, and the temperature gauge is staying right where it should. Thanks again for pointing me in the right direction. You saved me from going back to that sketchy mechanic who probably would've charged me triple for the wrong fix. Definitely keeping this new place for future services, it's amazing what a difference a knowledgeable mechanic makes with these hybrid systems!