I believe it is underneath the inlet manifold a bit of a sod to get at ,cost for the part is around 75ukps then fitting charge .I have never known one go faulty.

Edited by Collos25 on 17/02/2013 at 18:58

want to change because engine light came on so i took to garage and they plug it in and it said somethin about it not fireing propley and they checked it for me at no cost and said water had got round the plugs and they did this for me and clear the fault so the engine on my clocks went off and it was fine for couple days until i had my family in the car and the engine light came on again so i took the car back to were i buy it and they took me to a garage and they plug it in again and it came up knock sensor and them that sell me the car said they would pay for it sory about my spelling