E90 2006 BMW 330i power reduction possible limp mode please help!!

[Pleks22]

Okay so I have been having this issue with my 330i ever since I swap for a new battery and did the oil change I have not been able to drive it as it went into what I'm assuming is limp mode only one fault code pops up in that is p0156 however I cannot find that code on the internet for some reason it does not exist some say it's the 02 sensors but it is not the correct year and model for my car from the research I found. It ran fine before this happened. No check engine or service engine soon absolutely nothing I don't understand why it's in limp mode if that's the case. I have heard sounds of rattling underneath the car but it's not very loud is very faint and when I step on the gas and let it go it almost cuts off it revs right underneath to right under 2000 RPM I'm going crazy being stuck at home!!! Please help!!:eyecrazy

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Update*** yesterday just replace the fuel pump regulator right behind the driver side backseat and still nothing has changed

[jclausen]

Do the windows work? Because the frm module can be damaged just by changing the battery and the battery needs to be registered, I don't know if the frm would cause it to go into limp mode though.

[Pleks22]

Windows work I found out that I do need a register it my brother had put it in so I did not know well neither of us did but not only that pep boys which I just found out today gave us the wrong battery but I do have a reader this is what it said

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