DTC P0141: Ho2S Heater Performance - Bank 1, Sensor 2: Description

Heated Oxygen Sensors (HO2S) are used to minimize amount of time required for closed loop fuel control operation and to allow accurate catalyst monitoring. Oxygen Sensor (O2S) heater greatly decreases amount of time required for pre-catalyst oxygen sensors to become active. An O2S heater is required by catalyst monitor sensor to maintain a sufficiently high temperature, which allows accurate exhaust oxygen content readings further from engine.

PCM will run heater test only after a cold start, and only once during an ignition cycle. Cold start is determined by Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) at time of start-up. When engine is started, PCM will monitor HO2S voltage. When post-HO2S voltage indicates a sufficiently active sensor, PCM looks at how much time has elapsed since start-up. If PCM determines that too much time was required for post-HO2S to become active, this DTC will set. Amount of time HO2S should reach operating temperature is based on ECT at start-up and average Mass Airflow (MAF) since start-up. The higher average airflow, or higher start-up ECT equals a shorter time to HO2S activity.