Maybe this will help others. My '93 940 NA, Regina system, had an intermittent no-start. The last time it did that, I wriggled the crank position sensor cable and the car started.

When I replaced the sensor (an easy 10 minute job), I found that the rubber insulating cover on the old sensor's cable had deteriorated and split right at the sensor. When I connected an ohmmeter to the sensor coil and then suspended the sensor and cable in the same position as in the car, I found it took only a small twist of the sensor to short out the sensor coil. Thus the sensor would sometimes short out due to the motion of the engine. It never did this while the engine was running which still has me wondering why. It apparently sometimes shorted when the engine was turned off and then the no-start condition was set.

When I dissected the cable, I found the insulation on the wires inside the cable had crumbled and the bare conductors were very close to each other.

I couldn't see the split cable cover but I could have felt it if I had reached down behind the engine to where the cable goes into the sensor. If you have this sensor, you might want to feel the cable and replace the sensor if the cable has split. Also, this appeared to have the original sensor color stripe so it had likely been in the car for 10 years. As many have said, it was time for it to be replaced.