Never trust a code reader, have the items that the code reader said is bad inspected directly with an oscilloscope. Your explanation of the problem needs to be a more detailed explanation please. What was the code exactly. In order for a computer to go into Closed Loop, the oxygen sensors need to be fully hot and working. You mentioned circuit 2, that may be Bank 2 or it could be sensor #2. We don’t fully understand your problem, more details please. Also what is clicking? One of your fuel injectors is making clicking sounds?