[tomjonesBT33]

Folks - I'm a new owner of a well used 2004 Z4 2.5i. It has a few issues that I've been trying to diagnose over the last couple of weeks. I have searched many forums including this one and haven't found my exact situation.

One issue that I've been unable to pin down is a fault code 5E38 'Defective rotation rate sensor.' From my research this could caused by a bad yaw sensor, lateral acceleration sensor (if they are separate sensors which isn't always the case) or bad wheel sensors. I have INPA and ISTA-D up and running and I've measured real time data from these and the sensors are working. When this error is triggered (which can happen at different times, speeds, etc) during my drive, I get the usual BRAKE and triangle with circular arrow. But I also get the TPMS light too.

In INPA I try connecting to the TPMS module and get a IFH-0009 Cannot connect error. I cannot connect to this module in ISTA either. In INPA I can get access to the RPA function with monitor run flat tire deflation. I can reset the TPMS error icon in the RPA menu. Since this is 2004, I'm not sure my car should have a TPMS Ecu since this was not mandated in the US until 2007 or 2008.

First question: does a 2004 Z4 have a TPMS ecu?

Second question: if so, would a 5E38 error result from a bad TPMS module

Third question: if no TPMS module, would a 5E38 error be a result of bad sensors in the tires?

Fourth question: where does the RPA function reside? Is it a separate unit or built into the DSC Mk60 unit?

Or is the TPMS error light a red herring and I need to look for another potential source

Thanks for any insights