huh . . . ?
You told us what code you have, and we told you what p1121 means
It seems that your code reader is wrong
It seems that the APP sensor is not the cause for that code
A word of advice . . . make sure the shop that replaces the coolant flow control valve has the proper equipment to replace coolant on a hybrid vehicle
You need to use a machine that can suck out the old coolant, and suck in the new coolant under a vacuum, thus eliminating air pockets.