freelander td4 fault code p1613

Hi how are you doing? i bought a freelander facelift td4 2006 model it was running like a dream for a while.....for a while lol. I took my family to nelspruit for a mountain trip on our way there 5hours in the trip it got so cold the heatgauge seemed dead.and after that there was a injector knok i replaced all of them it starts easy smokes a little in the morning but fault code P1613 cylinder 1 correction? what could be the problem please i love the car but need to solve this before extending damage

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