Hello everyone! I was hoping someone could give me some advice based on their experience with a BMW.
My BMW 420i Gran Coupe is a 2014–2017 model with 76,806 miles and a manual gearbox.
I've been driving steadily at 60-70 mph on the highway when all of a sudden the power goes out for about half a second. Then it comes back on and drives normally, which is a really strange and intermittent problem.
There has been no slow dwindling of strength. For that brief instant, it's as if the vehicle becomes unresponsive. At that second, the speed won't increase no matter how firmly I plant my foot on the floor; then, out of nowhere, the power returns.
To try and find a pattern or rule anything out, I've experimented with various gears, driving modes (Comfort, Sport, and Eco Pro), and cruise control, but it doesn't make a difference. Up until this point, it has only happened to me on long car rides, and it seems to happen at random.
The fact that it happens so randomly is the most annoying aspect. It occurred again on Saturday after the previous occurrence about a month ago. The ECU is not displaying any error codes, warning lights, or discernible pattern.
German Auto Center has since performed a comprehensive diagnostic and health check on the vehicle that I had scheduled. There are no error codes to guide them, and they still haven't discovered anything wrong with the vehicle.
Even with real-time data, it's very challenging to diagnose events that occur half a second apart, let alone weeks apart. Not knowing what's causing it makes it seem like a needle in a haystack, and I'd rather not start spending money on replacing parts.
Is anyone else's BMW 420i or other petrol 4 Series dealing with something similar? Were you ever able to determine the root cause and the method of diagnosis?
I would love to hear from anyone who, while driving on the highway, briefly lost power without any lights or codes coming on, and what the solution was.
Even though it's brief, the fact that it occurs at high speeds on the highway makes it all the more worrisome because of the danger it could pose.
I would be eternally grateful for any help or insight you could provide. I'm crossing my fingers that someone will be able to identify these symptoms and give me some advice. I am grateful.