why my engine light keep telling me the crank shaft after already replacing it and the sensor?

Diagnostic fault codes never say to replace parts. They indicate the circuit or system that needs further diagnosis. A failed sensor is one possibility but there are many other things that can set the same code. Codes are especially helpful when you have an intermittent problem that doesn't act up all the time.

A scanner is usually needed to see what the Engine Computer is seeing from the various sensors. Without a scanner you might be able to diagnose the circuit with a voltmeter but it's a lot more work, and you'll need to understand how the circuit works.