I'm having some strange issues with idle and I'm starting to think the rear 02 sensor is at fault. Is there any way I can diagnose if it's at fault? Do testing?

My car runs alcatek ecu with updated idle control, I suspect the sensor is reading wrong though and causing issues

 

what voltage is the rear 02 showing with the car NOT running but the ignition on?

 

Good question, will check tonight. What would you expect?

 

Just plugged laptop in and alcatek figures:

Oxy_r 78/77
Lamb_r 376/381 mv

How's that sound? This is rear sensor used for idle control on my ecu.

 

Any thoughts on those readings jdm stig?