DTC P0154: Ho2S Circuit - Insufficient Activity - Bank 2, Sensor 1: Description

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The Heated Oxygen (HO2S) bank 2 sensor 1 is threaded into the cylinder 2, 4, 6 exhaust manifold (cylinders 2, 4, 6 are closest to radiator). The sensor is an electrical source that responds to oxygen content in the exhaust manifold. When the sensor reaches approximately 600°F (316°C), it is fully functional and produces a voltage based on the difference in oxygen between the atmosphere and exhaust gas. The ECM sends a 450 mV bias voltage on the signal line, which is pulled up through high resistance. When the HO2S bank 2 sensor 1 is cold, it produces no voltage and has extremely high internal resistance. The internal resistance of the sensor is much greater than the resistance of the bias pull-up resistor. However, when the sensor heats up, it produces voltage that overrides the bias voltage. This voltage is read by the ECM to determine a rich/lean HO2S bank 2 sensor 1 signal used to adjust injector pulse width. Under normal conditions, low sensor voltage means high oxygen content (lean air/fuel mixture) and vice versa. Normal sensor readings will fluctuate between 60 mV and 1080 mV. DTC P0154 will set if the HO2S bank 2 sensor 1 signal is inactive for a certain length of time.