This is how one club member fixed the 17589 fault code - http://www.a2oc.net/forum/showpost.php?p=45241&postcount=11
No guarantee's but its likely that changing this sensor will fix both your fault codes.
02 (oxygen) and Lambda are just different descriptions of the same sensor.
Note. before changing components its always wise to check for broken wires or bad connectors
Cheers Spike
the error code will indicate which sensor is causing the fault.