Failure of the hall sensor is quite common after all these years and the replacement assembly is no longer available from BMW. This repair kit is the best way to reignite your boxer.
To install, remove the two screws and then the cover of your hall sensor canister. Remove the large outer clip and then the small clip on the shaft to remove the rotor. Then remove the screws on the side of the canister to release the defective hall sensor and install the new part. Reassemble in reverse order.
this is a direct replacement and it includes the grommet, wiring and connector.