Duty-cycles of 2.6 or 3.4 don't mean anything. I would interpret those readings as zero on pin three.

You need a reference. I still don't remember what car we are talking about but you should have 70% duty cycle on most vehicles with the key on and engine off. Duty cycle readings of a fixed amount that is a multiple of 10 are codes and an active reading gives a function of control (relative mixture).

All cars should have a reading of 50% with the O2 sensor disconnected. Get your readings gauged to one of these constants before deciding what you have in active mode.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician