Hi Stu Thanks for the reply I dont know if the fuel pressure is correct i need to check it, the anti tamper cap is still in place though, car was nice and warm I waited for the fans to cut in and out before checking the CO I could have made it less than 0.9% but was miss guided by the guy that owns the equipment I.e if it was a CO value or Lambda value. The thing that concerns me is the large change in co between fans on and fans off?