If you have a JB4, what were the codes you threw? I had issues at first with the JB4 and it turned out that I had connected some of the wires incorrectly (pin out type).
About a year later I had some issues and one of the wires had come loose. I had to shut off JB4 and the car ran as it should until I fixed the wire issue. When in doubt, shut it off.
On occassion I will get codes for things such as boost issues, typically when temperatures change.
Having the ability to check codes while driving is a great tool.....found out my water pump was going to die soon, replaced it. Just found out my HPFP was going to die, replaced that.
When you throw a code, find out what it is, clear it. Turn off JB4 to see if the problem comes back. If it comes back it aint the JB4.
2008 335xi - 6MT - BMS JB4 G5i - BMS DCI - BMS OCC - BMS WW Meth - Spec Stage 2+ - Spec SMFW - 19" MVR Magnum's - KW V1's - TMS 12.5+20mm Spacers