DTC P0140: Ho2S Bank 1 Sensor 2 Circuit - Insufficient Activity: Description

The Heated Oxygen Sensor (HO2S) is a sensor used to detect oxygen-content in the exhaust. The Powertrain Control Module (PCM) supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal. The PCM monitors the HO2S signal during Closed Loop. To correct for rich or lean conditions the following must occur:

• The PCM adjusts the injector pulse width.
• The diagnostic runs once per key cycle.
• The HO2S 2 signal voltage is within 100 mV of the bias amount at start-up.