Cant connect pump to aio_pump header? CPU FAN ERROR

I recently bought an h150i, a "heavy duty" 360mm aio cooler from corsair, and when connecting it to my motherboard I went to the cpu_fan header and it worked perfectly but after staring at my pc cause its gorgeous I noticed to aio_pump header and decided to look it up on the mobo manual. my mobo is z370-h strix from asus (a board that apparently has 0 rgb headers. ffs) and It was indeed for the pump for the aio, so I disconnected the 4/3 pin connector (cant remember on the top of my head) from the cpu_fan header and connected it to the aio_pump, pc posted but told me: CPU FAN ERROR PLEASE CONNECT CPU FAN TO CPU_FAN HEADER or something along the lines of that... that was like 3 days ago so I dont remember correctly but I decided to reconnect it to the cpu_fan header. it works normal, temps are normal so its not a big deal if I cant do anything about it, but I wanna atleast know why it does this.

 


but I have 1 or maybe 2 fan headers, I have 3 fans... and they are all connected currently to the pump itself... my case is the h700i and it has built in fan headers and I could also use that but I was told to use the pump headers... what do I do if I dont have anything to plug into the cpu_fan