Code P0012

I have a mystery solver here, I got a POO12 on my scanner, so of course I went the cheapest first and changed out the VVT solenoid, but I guess that didn't work out. Car runs as usual but when you first start the car and after a minute a rattling sound starts by the pulley in the back. It doesn't sound much as the pulley itself and because I got P0012 i'm assuming something else. But yes I have changed out the VVT oil solenoid. I did not do an oil change yet and it has been awhile, but the rattling sound comes and goes comes and goes. Maybe someone got some good advice, ideas or pointers as to where I can look next? I really hate for it to be the timing because then that's over my diy level. Anyhow I would really appreciate some feedback and maybe I can take a video sometime tomorrow of what it actually sounds like.