P0131

[P0131] The scan tool indicates Diagnostic Trouble Code (DTC) P0131: A low voltage problem in the Rear Primary Heated Oxygen Sensor (HO2S) (Bank 1, Sensor 1) circuit.

The Heated Oxygen Sensors (HO2S) detect the oxygen content in the exhaust gas and signal the ECM. In operation, the ECM receives the signals from the sensor and varies the duration during which fuel is injected. To stabilize the sensor's output, the sensor has an internal heater. The Front Primary HO2S (Bank 2, Sensor 1)is installed in the front exhaust manifold, and the Rear Primary HO2S (Bank 1, Sensor 1) is installed in the rear exhaust manifold.