Six months ago I changed the crank position sensor, and the knock sensor. Now I'm going to change the cam sensor. Do all sensors have an expiration date? Any input would be greatly appreciated...

leave it alone unless you have a problem, dont fix something that isnt broken!

sensors are ultra reliable unless damaged by misuse.

I wouldn't think of changing it if all was fine...first sign was that it wouldn't start, so I took it to the dealer where they diagnosed the prob. I still don't understand though how you could misuse a sensor...