Well, my bad is that I didn't write down the fault code. I am sure it was related to bank 1 - wondering if there are seperate fault codes available for front and back sensors?
Peco84, thanks for the reply. What do you think, could the impendence checking while cold on both of these sensors reavel, which one is faulty?
you will have to get the code it will pin point which sensor is either faulty or reading a abnormal signal like lean or rich mixture.