Pull plug caps.Measure resistance from one to the other, putting the meter leads inside the cap and make certain it makes contact. Should read around 20K ohms. If open, pull wires from coil and test individually to determine if one is open or if the coil is open. Otherwise the ICU or Hall Sensor may be bad. With ignition on, plug out of hole and grounded carefully against the cylinder, flick the kill switch on and off if it sparks, the ICU is likely good.
All of this is assuming there is no spark at all, not intermittent.
Last edit: 2 months 1 week ago by 1872. Reason: correct grammer
If you have the BMW electronic ignition, then the tan 3-pin connector between the "bean can" and the harness sometimes disintegrates. Rick Jones at Motorad Elictrik sells a pig tail which will restore the connector and spark.