Its not very hard to change the cam pos sensor. Buy one sensor and replace one side and if that doesnt fix it then undo what you did and replace the other side. One thing Ive noticed is that the replacements from BMW is bigger than the original ones so check to see is any one of them was replaced allready and replace the older one. I bought my x5 used and when I changed my sensors out I changed just the older smaller one. I then reset the Service engine soon light at auto zone and the light never came back on. My car was giving to code p1340. Hope this helps.