the fuel censor, on common rail engines there useully at the end of the rail. I carnt find it, the box plug,s in an fools the pump into more fuel at the right time, giveing more toque . i bought 1 off the internet from energy tunning ltd, they sent me a diogram of the wrong engine. I ask what the #### was going on, all i wanted was a pic of my ingine an were to plug the censor. The guy got all ratty an said send it back an i will give you a refund. So much for customer care.