how do I troubleshoot OBDII code P0101 P? Is this a MAF sensor problem?

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I hope you can help me, or direct me to a site where I can access troubleshooting procedures for my '99 Z3 (it appears to have an MS52 TU engine). Specifically, I've got a problem that allows the engine to start but immediately die; it won't let the engine continue running. I've bought a manual from Bently Pub., an OBD codes manual from Haynes, and an OBDII tester: the only error code detected is "p0101 p". The manuals all say that code indicates a Mass Air Flow 'signal value error'. While I might assume that means an open circuit, none of my manuals indicate how to test the MAF sensor, which I've removed and now want to test; I don't want to buy a new one, then find out the problem is in the ECM computer (replaced 2 years ago with a 'rebuilt' unit for $3k) or elsewhere in the circuit. Can you advise me, or direct me to a website that can help me? Thanks in advance.