BMW 2 Series Diesel: Limp Mode & Sensor Issues

Hi there! I have some experience working on cars. I had a similar issue with my 2018 BMW 4 Series diesel last year. The symptoms sound exactly like what I experienced, limp mode and warning lights. Initially thought it was the sensor too, but turned out to be a loose connector near the oil temp sensor. Took it to my regular workshop, they diagnosed and found a damaged wire in the connection. They replaced the wiring harness and connector, total bill came to 95 Euro, which wasn't too bad. To help you better, could you share: Which engine variant you have? What error codes are you getting? Does it happen when the engine is cold or warm? I know BMW 1 Series and 2 Series share similar components, so happy to provide more specific advice once I know these details. Hope this helps!

Thanks for your detailed response! I have the B47 2.0L diesel engine variant. The error codes are P0196 and P0198, both related to oil temp sensor circuit issues. It happens mainly when the engine is warm, usually after about 15-20 minutes of driving. Last service was about 3 weeks ago at 185484 KM. Really hoping it's just a wiring issue like yours and not the sensor itself. Been a reliable car otherwise. Let me know if you need any other details to help diagnose this.

Hey again! Thanks for providing those details. You know what, this is even more similar to my case than I initially thought! I also have the B47 engine and got the exact same error codes. The timing of when it happens (15-20 mins into driving) is exactly what I experienced. Given that you're getting P0196 and P0198, which are specifically about the circuit, I'm now pretty confident it's the same wiring issue I had. When my mechanic dug deeper, they found that the wiring near the connector had started to deteriorate due to engine heat. The insulation was wearing off, causing intermittent connection issues. That's why it would mainly act up when the engine was warm. Since your car's been reliable and recently serviced, I really wouldn't worry too much about the sensor itself. My advice would be to have your mechanic check the wiring harness and connections first before replacing any parts. Could save you a decent chunk of money. Quick question, have you noticed any oil temperature fluctuations on your dashboard display before the warning lights come on? In my case, I saw some unusual jumps in the readings just before it went into limp mode.

Thanks so much for the additional info! That's really reassuring to hear it was just a wiring issue in your case. You know what, I haven't been actively monitoring the oil temp display, but now that you mention it, I did notice the gauge acting a bit weird last week, showing some sudden jumps. Just didn't think much of it at the time. I've booked the car in at my regular workshop for tomorrow morning. Will definitely ask them to check the wiring and connections first before jumping to replace the sensor. Really appreciate you sharing your experience, it's given me a much better idea of what to expect and what to tell the mechanic to look out for. The deteriorated wiring due to heat makes total sense given the symptoms. Will update once I get it sorted. Thanks again for all your help!