P0157 CHEVROLET - HO2S Circuit Low Voltage Bank 2 Sensor 2
Tech notesReplacing the Rear Heated Oxygen Sensor Bank 2 usually takes care of the problem.
When is the code detected?The Powertrain Control Module (PCM) monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, the P0157 code will set.
P0157 Chevrolet DescriptionThe Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.