Heinrich's is located in West Lawn on 422 West (Penn Avenue), between the Berkshire Mall and Sinking Spring. Headed west, they are on the left side, maybe 1/2 to 1 mile from the 4 lane to 2 lane transition.
I have not actually dealt with this shop, but I have talked to the owner and they have been in Reading a long time. I have never heard anything bad about them.
FWIW, I have my warranty/free maintenance work done at Horrigans. They are quite good, I have been impressed with their quality of mechanical work and customer service. But - I do all my own maintenance on the out of warranty cars, so I have never actually paid for their service.
http://www.bimmerdiy.com/e46 But they do not have any info on Cam sensor replacement.
If you have never done much work on a car, this is probably not a DIY for you.