I need to replace a thermosts on a 2001 Sentra GXE

Question edited for clarity.
Question moved to sub category.

All in the link. Click on images tab as well.

https://www.google.com/search?q=2003+nissan+sentra+gxe+1.8+fuel+system+diagram

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When a hot engine is hard to start, most of the causes are fuel related problems. Fuel cannot circulate well due to the way in which vapor blocks it.

To troubleshoot the problem with step by step details,click the link below:
http://carrepairworld.blogspot.com/2015/04/engine-hard-to-start.html

This will help.
Thanks

I had same problem on my 2001 sentra gxe, no crank but dash lights up. thought it was the immobilizer system. found a blown fuse in the panel under the dash drivers side. 10 amp fuse labeled engine control

Maybe your radiator is clogged.

you have a short in your dash lights try replacing it.

Take a few minutes to make sure you dont have a blown fuse....Run through them with your test light...

it is wher the engine meets the transmission..on the flywheel...and the oxygen sensors bank 1 is the one before the catalyst....and bank 2 is the one after the catalyst....

good day Sir, your nissan sentra 1999 gxe have a timing chain this is some tips for your routine maintenance.
Replace engine oil
Replace engine oil filter i

You will need a new catalytic convertor assembly. Yours is below treshold efficiency in other words its "no good".If you have it replaced, ask the garage/dealer to give you the old one back. Its worth some cash if its full. It doesn't matter thet it failed. They are going after the mesh inside of it and that is worth some $$$$. May not be much , but better than nothing.

It has a belt. You should replace it soon.