OHHHH, the dreaded code 41. I hate that code.. You'll know why in a bit.
The cam sensor, which is mounted on the timing chain cover, gets its signals from a magnet encased in plastic, in the camshaft timing gear. This is the chain driven camshaft, its the gear, that holds the magnet, and sends the signals to the ECM.
The problem with this design, is the magnet is encased in plastic, and plastic in an engine? Not good, it breaks down, and at the right moment, flies loose, (usually after you've done some racing with it, lol)
Shops charges vary arounds 500-900 dollars for replacement. The timing chain cover, waterpump, harmonic balancer, and everything else on the front end has to come off to get to the magnet. To replace the magnet, the cam gear has to be unbolted from the camshaft, which means, you'll have to line up the timing marks on the crank and cam gears. Its a big job. I was able to do this in 8 hours, with power tools.
You'll have to go to the dealer and get a new, as GM calls it, an interrupter. Also get a set of front end gaskets, and some permatex ultra copper sealer.
There are guys on the board who will chime in, they've done a cheap and easy way to replace the magnet---I don't recommend it, especially if you really rack up the miles on the car, theres no telling how long that job will hold up. The best solution is a dissassembly of the front end and replacement of the magnet.
Of course, you can do without. Its only there for the proper sequence of the firing of fuel injectors. The ECM will instead take the reference signals off the crank sensors to determine the firing of the injectors. It isn't exact, and as SFI (sequential fuel injection) performance suffers, your gas mileage is affected too, and the car may run like poo poo sometimes. I didn't notice much of a difference, but did notice gas mileage wasn't as great. I had to drive like this for 2 weeks till i could get the $$$ for parts, then i finally did it. I just hate check engine lites, lol.
Anyways, good luck, and any questions, just ask.