CPS on the 3800 is usually just to the left of the waterpump pulley. It'* screwed into the block w/ a single screw. Tragically, the sensor itself is NOT bad, but the the interrupter magnet on the cam gear has become dislodged. It'* just a small inexepensive magnet on the cam gear, but it requires that you pull the chain cover to access the magnet. This makes it a good afternoon'* work. While you are there you are usually wise to replace the chain and gears etc...
There is a way you can replace the magnet without taking off the cover, but it'* not easy and I'm concerned about the piece not staying in place in the holder. Honestly, pulling the cover is the best way.....not that hard, but you have to remove the HB to get to it and be very careful not to damage the crank sensor when taking the HB off.