Got a coil warning light on my golf 5 1.9 tdi which dissapeared and a couple days later turned into a check engine light , did a scan and got a camshaft sensor fault and an egr fault. Replacing the valve would cost me 200-250 at a shop . Does replacing the valve by yourself require a lot of knowledge and tools? Most I’ve ever done is change the air filter and I don’t want to mess the car up even more.