Chrysler
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    HO2S Remains At Center Conditions
Cause:
    Engine runtime over 2 minutes, ECT sensor input more than 176°F, then the test started and the PCM detected that the front HO2S-11 signal was 0.5v (fixed at mid-range) for 1 minute.

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 Circuit Open/Inactive Conditions
Cause:
    No Engine Sensor or Misfire codes set, engine runtime 1 minute, ECT input above 140°F, in closed loop A/F ratio at 14.7:1, throttle angle off idle over 6.5%, then the PCM detected that the HO2S-11 signal remained from 391-491 mv, condition met for 90 seconds.

Nissan
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Heated oxygen sensor (HO2S) 1, Bank 1 - excessively high voltage
Cause:
    Wiring, HO2S, ECM