Fault code

[elj]

Car has been going into limp mode when cold so I bought a fault code reader and its telling me that there is an O2 circuit sensor malfunction on Bank 1 Sensor1. I think this is the lambda in the manifold going wrong but could someone confirm or advise if both lambdas are the same and where can you buy them cheaply? Assistance appreciated

 

[bozothenutter]

The sensors are the same, just the lead is different (longer) the longer one is the one in the manifold.