I have a 2016 Elantra that sometimes starts but will not crank. It will crank with a boost off. I have replaced the battery. The oil pressure switch has been replaced as well.

 

It probably would be a good idea to begin with talking the same language.

When we are attempting to start the engine , we say it cranks over Then it either fires up and starts running or will not start running.

Now I hope you can see where confusion gets into the picture.

If the engine cranks over but does not start, can be one group of causes.
If the engine will not crank over , it cannot start, and that would include a different group of possible causes.

If I understand you correctly it will start with a jump start , but not with a new battery.

What we are doing when we jump start is ,,,,by passing the connections at the battery because jumper cables are connected directly to the vehicle.

One check you can try is,,,,,turn the headlights on. Are they at the normal brightness? Then watch what you get when attempting to crank over the engine to start it

Either the lights will go dim or out or no change at all . If they go dim , either insufficient power available from the battery or a starter problem.
If they go out , poor connections with battery cables or battery very low.
Get back to us if you can with the results of those checks, thanks.

 

If its starting with a jumper from a different battery but does no start with a new battery. May be check your starter, an instrument cost around 10-12 dollars can check your starter as well s battery. its a handy device specially if you have no idea when the battery was added.

 

My car started stalling on me last Monday. When I got it started, the check engine light came in. I took it to Oreilly and had it put on the machine. It came back with a code for the crankshaft sensor. I had the sensor replaced and haven’t had any problems since