Hi New to Nissan's and the site. I just purchased a 97 pickup witha 4cyl and 5 speed trans. It has 322,000 miles but has no rust .It runs good but the service engine light is on. And to pass imission insp the light must be out. It has these codes 335, 400, 443 I checked the manual for the description of these but it seems a little confusing to pinpoint a answer. Can any one point me in the right direction or should I let the dealer tell me what needs to be replaced. Also where is the Crankshaft positioning sensor located? Thanks in advance.

Ok. Here's what I could find for you, hope it helps get you started.
P0335 Crank Sensor. Located on transmission housing. Reads off the flywheel.
P0400 EGR. Typically means PCM is not detecting EGR flow when required. Look for any broken vacuum lines! May also be bad EGR!
P0443 Evap. Canister Purge Control valve. Check wiring going to evap canister. Test components on canister to ensure solenoids move!

I know I haven't gone into too much detail, but hopefully this will at least point you in the right direction. Don't know what your skill level is, but if you have a good manual and multimeter, you should be ok!
Good luck in your efforts!

Heres a update. I found a broken vacume line on the EGR valve tubing, And I replaced the Crankshaft POS Sensor. So I cleared those two codes. But I need to deal with the 443 code. My scanner says Its the Purge valve selonoid. I can't find one online. Does anyone know the cost of this Part? Should I take it to the dealer to make sure that this is the right part that needs replaced? As soon as I get this last code cleared I will be able to get my Inspection.

Honestly a purge solenoid is a very simple device and should be pretty easy to replace if you can find a replacement, I would try just replacing it yourself first before resorting to a dealer cuz they will charge you an arm and a leg. Have you tried calling your local parts stores to find a replacement?

I am not sure which valve it is. The local parts stores only have the vapor canister purge valve. What I think I need is on the pass inner fender. It has 2 Vacume lines and a plug with about 6 wires? I don't have a problem changing it I just want to buy the correct part. By the way this is my first Nissan.

The vapor canister purge valve should be what you need if you're scanner is correct. Try going to the store and asking to see the part if they have it in stock, that way you can see if it's the same as the one you're seeing that you think needs replaced.

this is a diagram showing all vaccum parts for your system. Take a look at it and see which part you need.

One site where you could possibly buy online is http://www.nissanpartszone.com/componen ... -1064.html

This should give you a general idea of how much your part will cost new before a dealer markup. You could probably find a cheaper alternative out of a junkyard or at autozone and such. personally I like to stick with oem parts though.

edit:
the part at autozone is part# 911-500. it's $86.99

here is a picture of the part:

Thanks for the help. I took the truck to the Nissan dealer to Find out which Sensor was Bad . They said is was the one Numbered 14956V that was located on the the right inner fender in the above diagram. Changed it and reset the code and the same code number 443 came on after 10 miles. Accord to the service manual this is the sensor that causes this code. Also I stop for gas and when opening the fuel cap there was a whooshing sound when removed. I reset the code and then drove about 14.5 miles and the light hasn't returned yet. I am going to drive it later and see what happens.

Sound from the gas cap is normal, if it doesn't make that sound you need a new gas cap.
As for the code returning that probably means the solenoid wasn't your problem, you may have a leak or a wiring issue.

Took the truck out and didn't get a 1/2 mile the Light returned. I checked with my code reader and this is what it said/
PO443 EVAP Emission Control System Purge Valve C Fault. So Nissan got away with a 100.00 for the part part, Thank God I didn't let them get me for the 86.00 Labor

To cause a P0443, there has to be a problem with the purge control CIRCUIT, not necessarily the valve. Usually they are a unit housing the valve and the solenoid as an assembly. Or it could be comprised of a separate solenoid with vacuum lines to a purge valve. That said, it could be any of the following:

Bad purge solenoid (internal short or open)
Wiring harness chafing or rubbing another component causing short or open on control circuit
Connector worn, broken or shorted due to water intrusion
Driver circuit inside powertrain control module (PCM) is bad

Thanks for all the replies I got a emission wavier on Friday .So I can get a state inspection done on Wed. This will give me a year to find out the problem.

it would suck if it's an electrical issue. make sure you don't have any bad vaccume lines near the solenoid.