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 170-176°F, then the test started and PCM detected that the front HO2S-21 signal was near 0.5v 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 Insufficient Activity Conditions
Cause:
    No AIR, ECT, EVAP, IAT, MAF, MAP, Misfire or TP sensor codes set, DTC P0155 not active, Decel Fuel Cutoff not active, Catalyst and EGR Tests inactive, no device controls active, system voltage over 9v, engine runtime over 2 minutes, system in closed loop, ECT input more than 140°F, MAF input 10 g/sec or more, then the PCM detected the HO2S-21 signal was fixed from 300-600 mv, condition met for 80 seconds (over 40 seconds on 7.4L V8)

Nissan
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Heated oxygen sensor (HO2S) 1, Bank 2 - excessively high voltage
Cause:
    Wiring, HO2S, ECM