BMW Check Engine + Power Loss, Sensor May Be Culprit

Hey there! Had a similar issue with my 2008 BMW 3 Series last month. The symptoms matched yours, check engine light, reduced power, and the car running in limp mode. Took it to the garage and they found a cracked exhaust manifold along with a faulty oxygen sensor. The leak in the exhaust system was causing incorrect readings, making the engine run rich. It turned out to be a serious issue that needed immediate attention. The crack was allowing exhaust gases to escape before reaching the catalytic converter, which explains the increased fuel consumption you're experiencing. Left unchecked, it could damage other components. In my case, they had to replace the exhaust manifold and oxygen sensor. The repair took about a day and a half. I'd definitely recommend getting it checked soon, these symptoms usually don't fix themselves and can lead to more expensive repairs if ignored. A certified BMW specialist would be your best bet for this kind of issue. They can properly diagnose it with their diagnostic tools. Hope this helps.

Thanks for sharing your experience! It sounds very similar to what happened to me. I took your advice and went to a BMW specialist. It did turn out to be a cracked exhaust manifold in my case too. Quick question, do you remember roughly how much you ended up paying for the full repair? Also, has everything been running smoothly since the fix? I want to make sure I won't run into any related issues down the line. Thanks again for your help!

Hey again! Happy to update you! Since I had my BMW fixed last month, it's been running like a charm. The mechanic found and fixed the faulty exhaust temperature sensor, plus they sorted out the leak in the exhaust system. Total bill came to 265 €, not too bad considering what could've gone wrong if left unfixed! The car's performance is back to normal now, no more check engine light, full power restored, and fuel consumption is back to what it should be. Honestly, it feels like driving a different car! The engine's running super smooth, and I haven't had any related issues pop up. Quick tip though, keep an eye on your exhaust system during your regular maintenance checks. These problems can creep up again as the car ages, but catching them early makes a huge difference to your wallet and the car's health. Really glad I could help point you in the right direction! Let me know if you need any other advice.

Thanks so much for the detailed follow-up! Just got my car back from the shop yesterday. The repair cost was a bit higher for me at 320 €, but totally worth it. You were spot on about how it feels like a different car now! I learned my lesson about timely repairs the hard way. The mechanic showed me the damaged parts, and honestly, I'm lucky I didn't wait any longer. The car's running great now, super responsive, and I've already noticed I'm using less fuel. Really appreciate you sharing your experience, it gave me the push I needed to get it checked out properly. The BMW specialist was fantastic too, way better than my old mechanic. They walked me through everything they were doing and even gave me some maintenance tips. Think I might stick with them for future servicing. Sometimes paying a bit more for quality work is just worth it in the long run. Thanks again for all your help with this!