BMW X3's Sudden Power Loss & Jerking Engine Mystery

Hey there! I faced similar issues with my 2019 BMW X4 last year. The jerking and power loss started after I had gotten a third-party chip tune. The car threw multiple fault codes and eventually went into limp mode. Turned out the aftermarket tuning had messed with the engine control unit (ECU) mapping. The dealer had to reset the ECU to factory settings and flash the original software. They also had to replace a damaged O2 sensor that got affected by the aggressive tune. It was quite serious since improper tuning can cause long-term engine damage if not fixed promptly. I learned my lesson about going to unauthorized tuners. The whole thing took three days to fix at the dealership. If you've had any recent modifications or tuning done, I'd strongly suggest getting it checked at a BMW dealership. These symptoms usually don't fix themselves and can get worse over time.

Thanks for sharing your experience. That sounds exactly like what I'm going through right now. Did you remember roughly how much the ECU reset and sensor replacement set you back? Also, has everything been running smoothly since the repair, or have you noticed any other issues pop up? Just trying to get an idea of what I might be looking at here with my X3.

Hey again! Great news, got everything sorted with my X4! After seeing the mechanic, they confirmed it was indeed a faulty chip tune like I suspected. The reset and software flash did the trick, no more fault codes or jerking issues. Cost me 180 € total, which honestly wasn't as bad as I expected given how worried I was about potential engine damage. Car's been running like a dream since then, smooth power delivery and no warning lights. It's been about 8 months now, and I haven't had a single issue pop up. Really glad I got it fixed when I did instead of waiting around hoping it would fix itself. Word of advice, stick to authorized service centers for any ECU work. Learned that one the hard way! Those third-party tunes might seem tempting, but they're just not worth the risk to your engine. Your X3 should be back to normal once you get the proper reset done. Let me know how it goes after you get yours fixed!

Thanks everyone for your help and suggestions! Just wanted to update you all on what happened with my X3. Finally got around to taking it to a certified BMW mechanic yesterday. Turned out it wasn't as serious as I feared, just needed an ECU reset and a quick software update. The mechanic was super professional and walked me through everything they found. Cost me around 200 bucks, but honestly, it was worth every penny. They had my car running smoothly again within a few hours. The jerking's completely gone, and the engine's back to its full power. Such a relief! No more fault codes showing up either. Really glad I didn't put this off any longer. Lesson learned, sometimes it's better to just bite the bullet and get things checked out by the right people rather than worrying about what might be wrong. Thanks again for pushing me to get it properly looked at!