[coriducu]

Hello guys
I have a Mazda-BT50,2.5D,2008 in garage,was need to change piston+rod+2valves+2cam followers and timing belt,after timing was broken.No any problem,but now wen I start engine I get a error code without much explanation give by Mazda IDS.(v88.05)
P1391-GPC Low Imput Bank 1 and nothing else searching on internet I found that this code for Ford(same car as Ranger hope to be same for Mazda),is referring to preheating system,but before I fit glow plugs , I checked and all seems to be ok .I try to erase DTC but every time I start engine the check light is lighting and error is same.Can somebody advice me what mean that Low Imput Bank 1,and what should I check?Idea is that in my country this kind of car are rare and same spare parts cannot be found,just by OE.I not like to bring plugs,and problem to be in other side,putting client to pay for something is good .It is not professional + not my intention
Please if someone can point me in right direction
Thanks in advance