My check engine light is on. My friend said he was getting a fault code of 26?

while car was idling I pulled one by one connecter off each injecter, there was one that made no change from when it was on and then pulled off and put back on. All the other injecters slowed down when disconnected and then increased when reconnected. Would it be safe to say that I could replace that injecter? try to clean it? I priced nthem at $35.Thank you soo much for time! You have been a great help!