DTC P0141: Ho2S Bank 1, Sensor 2 Heater Circuit: Description

WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

Heating elements inside the Heated Oxygen Sensors (HO2S) minimize the time required for the sensors to reach operating temperature, and to provide an accurate voltage signal, the HO2S heater operation is controlled by the Powertrain Control Module (PCM). The HO2S 2 is supplied power from the external ignition 1 voltage circuit. The PCM controls the HO2S 2 heater low control circuit with a low side driver. The HO2S 2 heater diagnostic monitors the current draw through the low side driver when the engine is running. The HO2S 2 heater diagnostic will run only after a cold start. To determine if the engine has been started from cold the PCM compares the Engine Coolant Temperature (ECT) at key on to that at the last key off. The ECT difference and the average Mass Airflow (MAF) since start-up determines how much time that the HO2S 2 should take to produce an active voltage signal. If the PCM detects an HO2S 2 voltage signal with a slower than expected time to activity, P0141 will set.