I have a 04 Mitsubishi Galant that recently died I put in a code reader an camshaft sensor popped up I also know alternator is bad I replaced it and the car still won't start what could be wrong?

Does the battery die after it runs for 7min? is that the only code you are getting?

This video may help ... the sensor is underneath the timing belt cover so it is a bit involved to get to ....
https://www.youtube.com/watch?v=RHMe3S7RQ68

If I recall correctly, the '94 2.4L does not have a crankshaft sensor. The timing is handled by
a) correct alignment of the timing belt; and
b) the camshaft sensor on the end of the engine, above the gearbox.

I have no experience of the V6 models.

I am assuming the engine will run. It could be a wiring problem or the cam and crank are not in sync.
I would need to know the actual codes to give more detail.

When replacing any sensors you have to tell the CPU that something was done so reset using a code reader.

its your camshaft sensor located behind the passenger side wheelwell i do not know how to fix though hope i helped somewhat

Probably behind the camshaft sproket. Do you see any wireing going into the timeing cover? how hard is it to remove the top timeing cover & have a look should only be a few bolts

have a code reader put on it again and see what it says

It's possible that the sensor needs to be rotated. The sensor is keyed so it can only be installed in one position. The camshafts spin once for every two revolutions of the crank, so it's possible that the sensor is 360 degrees out of phase (I've had this happen on timing belt jobs on other cars - with the sensor out of phase, the car would start, and then trail off and die within a few seconds). What you can try is to carefully remove the sensor, turn it over to see the part that mates to the cam, rotate it one full revolution, and then put it back on. Try that out and see if it helps. If it does the trick, great. If not, post back up and we can try to go from there.

It seems like a ground problem. First check all fuses to see that they have a good contact. Second, verify the battery terminals for good contact. Third verify the charging condition in the alternator battery system., remember shoul be around 14volts with car running.