what are some of the reason changed both cam sensor

 

What? Sorry, it doesn't make sense. Ask it again.

 

Welcome to the site.
I'm going to guess that the question is "what would be the reasons to replace both cam solenoids".
If this is so the answer I would give is you do not have to change both but your are right there it's only a few extra bolts.

Also one has failed the other one may not be too far behind. If one has failed because it clogged from lack of oil changes then the other one would be in the same condition

 

I'll guess.
Maybe you changed the sensor when you should have changed the solenoid.
Two different parts.

 

When that error popped up on my HHR, the suggested repair was to change the intake solenoid, exhaust solenoid and cam positioning sensor. My HHR acted up once and I had the repairs done by "my" mechanic that I trust. Even though when I took the HHR to the shop it ran "normally", but that was the first engine repair I have had to have done on my 06 HHR(125,000 miles). If you do it yourself, just determine which solenoid caused the error code and replace that one. How to do that is a mystery to me.

 

welcome to the site, I found this thread posted by Whopper awhile ago, for you to have a look at
www.chevyhhr.net/forums/showthread.php?t=28779
it might be of assistance, it has pictures!!