A lost crank signal will cause your engine to shut down. It will not restart until the signal resumes. The problem here is that a shop will have to diagnose this and they can only verify it if it happens while they are checking it. Do you have your check engine or service engine soon light on? If it is on, your computer may have stored vital information that the technician will need to help verify the problem. If there is no useful information stored in the engine control module the technician will only see that everything is working normally until the problem occurs. Everything is working if the vehicle is running. They will need to either shut down while they are graphing the crank sensor in correlation to other sensors
or have it not start for them to see what is missing.