P0300, P0302, P0304, P0306, Engine running rough with little power

[jfoj]

The typical OBDII DTC or trouble code is a single Letter followed by 4 numbers. Example PXXXX where X is a number between 0-9.

The few times I have seen DTC's or Trouble Codes with a 2nd letter the letter seems to be in the last character position and tends to appear to be a Hex value A-F. I have seen this before mainly on some BMW's. Unclear if this is the way BMW has presented the value or if this is a Manufacturer Proprietary code that comes through as a generic code but in the wrong format??

Anyway the majority of these codes I have run into on BMW have to do with the MAF. It is pretty obvious that the MAF on your vehicle is not responding.

I do not know the N52 like I know the M54 engine. However, I assume the MAF on your vehicle is a typical modern MAF that has both the IAT (Intake Air Temperature) sensor and MAF all integrated into one assembly. Most of this design MAF has 5 wires or connections, sometimes the actual connector may have 6 cavities, but only 5 connection are used.

I do not have the connections committed to memory and your engine may be different. I recall there is a 12 Volt switched feed and the other 4 connections make their way back to the DME.

You need to check for loose female terminals, power, broken wiring or continuity back to the DME connectors.

The MAF could just be bad a well, but this is an expensive test to rule out other problems.

You could try to source a used MAF on Ebay for cheap and hope it will allow you to determine if your MAF is actually bad or if you have a wiring problem. I would not buy a "new" cheap ebay MAF as most of these are Asian counterfeit units that do not work correctly. You will end up replacing any cheap ebay or parts store MAF with an OE supplier from a valid and known good parts vendor.