[Efthreeoh]

Not a flame... Just to reiterate if anyone reads this thread...

The is a perfect example of why one should never let a non-BMW trained technician work on a BMW. Even something as typical-appearing as a battery change is not as simple as it is with other cars. The Autozone-trained parts guys was following his training that said to keep factory presets for the radio, etc. plug a battery module into the OBD port, which caused problems. Additionally, the installer was unfamiliar with the IBS function (and cable) and failed to properly re-connect the battery to specification.

I can see with the IBS not functioning properly, some battery-related controls would not operate correctly. The E90 has a REST heat function that operates the water pump without the ignition on. The ECU keeps track of coolant temp so once the coolant is below a specific temperature, it turns off the water pump, which is also tied to battery health, where the ECU will not run the REST heat function if the battery is not healthy enough to run the water pump and the HVAC blower for an extended length of time. I would think the ECU gets that data from the IBS. If the data is not present, the control of the water pump could be affected.