Why doesnt my nissan altima shift

SOURCE: engine speed signal circuit

there is currently a recall being performed on altimas and there is also a updated crank position sensor check with your dealer for open recalls on your vehicle (its just a phone call away have your vin # ready (located on left bottom of windshield if your facing it from in front of vehicle it is on lower right side of windshield - also look on driver door jamb.

SOURCE: 2003 nissan altima 2.5s transmission rough shift

Probably sensors! I have already replaced the crankshaft positioning sensor once, nissan replaced it once under recall and now it is bad again! Plus my speed sensor is bad too! Go to any part store and get diagnostic test ran, it will tell what sensors are bad.

SOURCE: 2003 Nissan Altima?

Where is the sensor placed on the car?

SOURCE: 2003 Nissan Altima 2.5S, Check Engine Light Problem.

this problem could be caused by the mass air flow censor, i had the same problem with my car. it is really pricey at the dealer so you might want to check elsewhere for this part. I found one at a scrap yard for 85% less that the dealer and i also got life time warranty, the dealer does not offer any warranty on this part.

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.