I have a 2003 nissan altima and it will crank however if i cut it off for a few minutes it will not crank back up

SOURCE: 2003 Nissan Altima?

Where is the sensor placed on the car?

SOURCE: 2003 Nissan Altima heat problems

take to dealership , that also is a recall problem with alot of altimas , they need to flush system and check water valve , got mine fixed working great ever since , never hesitate to ask dealership about recalls , they have to fix for free

SOURCE: CRANK SHAFT POSITION SENSOR 20002 NISSAN ALTIMA

1st, Nissan had a recall on Crank position sensors for 2002-2006 Altima's. Check with you dealer before you go doing any repairs. You may discover you can get your car repaired at no charge.
NHTSA Campaign ID number :O7V527000
Symptom: Erratic behavior. Stalling and no starts and very difficult to diagnose due to the time frame in which the component actually malfunctions. The warranty should not be limited to the original owner.
I would also need more specifics as to which engine you have so I might assist you in where the location of the sensor is. The Altima had a 4 and a 6 cyl engine offered that year.

SOURCE: Crank position sensor for 2003 Nissan Altima

a crank position sensor , sends a signal to pcm about crankshaft position signal, the sensor controls spark timing and firing order. the signal is also used for pcm to detect a missfire!! it also sends this info to ignition module, any mechanic can replace a crankshaft sensor!! call a auto parts store and see if you can get one, the cost should be a lot less.

SOURCE: I need a diagram for a 2003 nissan altima

Here is a link to the diagram you need...

http://www.gates.com/common/part_locator/view_diagram.cfm?id=S6018