I have a Nisan sentra 2001 with the 1.8 engine. I keep getting code po335 Ive changed the cam sensor and crank and the code still pulls up. any ideas?

Here's a link to your code P0335. http://www.obd-codes.com/p0335 The sensor you took out is good.

Check to see that the wiring going to the cam sensor is good. Have you pulled the codes? If not, you should get a code reader. If you pull a P0016 code, then it's mechanical failure. Your timing jumped.

This pair of codes are related to the cam sensor.
Carefully check the cam sensors connectors and cables.

You have to rule out the timing belt first.
You will need help for a friend crank the engine while you view /feel the cam movement.
NO cam movement equal broken timing belt.
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If the cams move then it is save to swap out the cam sensors,

The car only blue books for about $3000. I hate to suggest it but financially it may be better to cut your losses on this one. A used engine with 7000 miles on it for this car could have been purchased for $1200.

The code that you are getting does not necessarily mean that the crank sensor is defective. Those codes are to be used as symptoms only. If the crank sensor is bad the car won't run at all.

If it's running rough you need to check the health of the ignition system, fuel system, and the timing.

Starting with the easiest to the more difficult.
1. Pull the spark plugs and read them. Are they fouled/damaged/wet/burnt?

2. Check the engine compression. Is the compression low?

3. Check the timing marks. Did the timing belt slip off a tooth with the cam gear? Is the timing belt worn out? Make sure these marks line up with what your manual shows.

4. Check your fuel pressure with a gauge. Does it match what the manual states it should be?

5. Is the coil pack weak, out of tolerance? Check it with a multimeter, make sure the ignition wires are in good shape. If you've never changed them, this would be a good time.

If you check these things you should find the problem...throwing parts at it till the problem goes away is the most expensive way to fix it.

The crank and cam sensors produce ac voltage that is sent to the computer. There are magnets or components on the crank and cam that the sensors "read".
The problem could be the harness between the sensors and the computer, or a mechanical problem like a timing chain or gear.

what is the code number for the check engine light??

I would google the code and see what other owners did to correct the problem. It may be an electrical short or lose connection in harness.

Are you sure it was the crank sensor that you replaced? The cam and crank sensors look identical. Was the engine hard or slow to start? If so, this will sometimes set this code.

P0335 and P0336 Engine crank sensor malfunction
To test this code, have a visual inspection of the location and wirings of the crank sensor. If the engine has a cam sensor, you might mistook it as the crank sensor (it is a good idea to contact ATS that can research this for you). Check the sensor wires for insulation making sure it is getting a voltage signal as shown in the wiring diagram. Sometimes, the wires itself is soaked with dirty oil causing the sensor to fail. If OK, check the engine timing belt system for any slack which can also cause the sensor to throw in the code. If all of these prove OK, remove the crank sensor and check it for resistance as compared to the standard specs. Lots of times, if the sensor probe end is contaminated with oil or cracked, this can only be revealed after the crank sensor is removed

I can tell you what code p0335 is :
Turbocharger Boost Sensor A Circuit Malfunction.