I have a similar intermittent fault on a 2002 4.4i .
I pulled some codes with a handheld diagnostic reader . BMW code 80 transmission switch using BMW specific scanning and also some P codes using OBD 2 scanning .
I then used INPA and got this - signal AGS code 80 90 2C .
I then used BMW DIS and got these -
code 60 selector lever switch
EGS - 3C EGS transmission switch .
You can dig deeper with DIS . The link posted by RRPhil shows the " L " wires .
DIS will tell you which configuration should be " open " or connected to " terminal 15 " .
DIS showed me the actual configuration at the time the fault happened and in my case L1 was open when it should have been connected to terminal 15 so the L1 connection is suspect .
One of the pics Phil posted shows in a blue icon which wire is connected to terminal 15 in the relevant selector position . So , in my case when in park it should have the icons at L1 L2 L4 , same as the pic but when the fault happens L1 is not making contact .

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