17539 O2 Sensor B2 S1 Internal resistance too high
17521 O2 Sensor B1 S1 Internal resistance too high
(P 1131-35-10)
This has only appeared in the last 10 days!

Could it be a problem with the internal heating elements?
Not noticed any difference in performance, but could it cause trouble?
I replaced both the lambda sensors a few weeks back, so any one got any idea's?