OK,my wifes car hasn't shown any problems or symotoms,yesterday she went to the store,and went to start the car,no start,I got there,1st thing I checked was spark,none there.

My 1st thought was the crank sensor,but do they go bad without warning? I don't want to arbitrarily just start buying/swapping parts.

The crank sensor on my '93 940 (same engine I think)failed and gave intermittant no-start until finally, no start at all. When I pulled the sensor, I found the failure mode. The rubber jacket had split open right at the sensor. There are three wires inside the jacket. The insulation on these three wires had flaked off. This left these wires hanging vertically very close to each other. My theory is that small engine movements when the engine was turned off would allow these wires to touch and the engine would not start. Repeated cranking might just cause enough movement to allow the wires to separate and the car would start.

I couldn't see the split in the jacket but I might have been able to feel it. If you have high mileage or the sensor is old, I'd go ahead and replace it. The one I bought was under $40.

The tachometer should move slightly when cranking. If not the Hall effect sensor is bad or possible the power stage. If there is no spark, it is most likely the Hall effect sensor. See FAQs for plenty of good info.

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Paul NW Indiana '89 740 Turbo 110,000

The tachometer should move slightly when cranking. If not the Hall effect sensor is bad or possible the power stage. If there is no spark, it is most likely the Hall effect sensor. See FAQs for plenty of good info.

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Paul NW Indiana '89 740 Turbo 110,000

Check to see if the fuel pump is running. If not, I think you may be on the right track. No spark and no fuel often means sensor failure, but not always. The sensor is an electrical component, and yes it can fail without warning even if it is not the usual path of failure. If I rember correctly, this sensor is a magnetic reluctance sensor. Basically it is a coil of fine wire around a magnet. There could easily be a break in the wire after years of thermal cycling and vibration.

Don't forget to check the fuel system relay and fuses. I only mention this as I tend to forget to check the simple stuff first. Does this make me a Volvocondirac?

Good luck,
Dan

First thing i would do is check your coil is it bad? they will deff abrut go bad like that. it possible that one of the connecting wires may have broken.