Okay. Maybe I am missing something that he knows.
Is there any history to this? Does the engine start and run? Or did it run and then just stop one day?
If you look at this first attachment it gives the possible causes. If you look the first two are wiring issues, the next is a possible misalignment of the cam and crank pulleys, the last is the sensor.
The only way it would be the cam and crank pulleys being misaligned is if the belt jumped a tooth, or it was not put back together correctly. Again, this is why I am doubting it is the belt because I didn't read anything like that happening. Also, if he checked the signal he should know if he is getting a proper signal. The proper way to diagnose this being a timing belt before he tears it down to look at it, is to use a lab scope.
With a lab scope he needs to look at the cam and crank patterns to see if they are lining up properly. I attached sample. This is off of a Chrysler product so your pattern is going to look different but the idea is the same. If the belt is causing the issue, then the cam and crank sensor will not line up as they should. If he as not done something like this then he is going to be doing a lot of work to tear this down just to look. If he doesn't find anything then you will be right back where you are right now. So unless he has some sort of proof that this is the issue, I would just ask if he is going to charge you to check the belt if that does not fix it.
Images (Click to enlarge)
Sunday, August 25th, 2019 AT 4:08 PM