The cam shaft position sensor is also part of the oil pump drive assembly.
The cam has a gear on it, that turns a gear on the cam sensor, which rotates a shaft.
The top of the shaft has a rotating disc that the sensor reads.
The bottom of the shaft inserts into the oil pump and turns it.
So if it gets bad enough, the gear will fail, the shaft wont run the oil pump, and about 2 minutes later your engine will be toast.
03 to 06 Jeeps (especially 04 and 05s) are VERY prone to have these gears prematurely wear.
There is even an official letter that was issues to dealers on this, called the E05.
For the most part, dealers seem to be replacing these under the drive train warranty.
Symptoms Include:
Ticking
Squeeking/Squealing (especially at startup)
Long Cranks to Start
Low/Rough Idle
The Cause:
Many cam sensor/oil pump drive assemblies made in 04 were defective.
They are not shimmed properly, which causes the gear to ride funny, and not mesh with the cam gear properly.
The eventually causes premature wear on the sensor gear. The cam gear is a harder metal, so typically it wont see nearly as much wear.
Which is a good thing, replacing a camshaft is about a $1100 repair.
You can pull the sensor and visibly check it yourself, BUT.
be aware that this works like a distributor cap, you have to put it back in the EXACT orientation it was.
If its turned slightly, it will be out of time with the cam, and the sensor will read wrong.
Source:
http://www.jeepinwv. com/forum/viewtopic.php?f=4&t=21232