Chrysler
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    HO2S Remains At Center Conditions:
Cause:
    Engine runtime over 2 minutes in closed loop, ECT sensor input more than 176°F, then the test started and the PCM applied 5v to the rear HO2S-13 circuit for 30 seconds and then detected that the rear HO2S-13 signal was fixed between 0.39v to 0.52v (condition met for 30 seconds).

Generic
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    O2 Sensor Circuit No Activity Detected

GM
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    HO2S Insufficient Activity Conditions
Cause:
    No PCM or TCM codes set, engine runtime over 4 minutes, then the PCM detected the HO2S-13 signal remained from 425-475 mv, condition met for over 50 seconds