P0131

Diagnostic Chart:

Schematic:

When the Oxygen Sensor (O2S) reaches approximately 318°C (600°F) it becomes an electrical source that responds to the oxygen content in the exhaust. The PCM produces a bias voltage of approximately 450 millivolts on the oxygen sensor circuit. When the sensor is cold its internal resistance is extremely high, therefore the PCM recognizes the bias as an open circuit. As the sensor warms up, the internal resistance decreases. When the sensor reaches approximately 318°C (600°F), it starts producing a voltage based on the oxygen content in the exhaust stream. This voltage is used by the PCM to determine a rich or lean oxygen sensor signal and adjusts the fuel mixture accordingly.

DTC PARAMETERS
DTC P0131 will set if the O2S sensor 1 voltage is less than 43 mV for 125 seconds when the following conditions have been met for 20 seconds
^ Engine coolant is greater than 70°C (158°F).
^ The system is in closed loop mode.
^ TP angle is between 8% and 50%.
^ Air flow is greater than 3 grams per second.
^ Fuel level above 9%.
^ DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0301, P0302, P0303, P0304, P0336, P0440, P0442, P0446, P0506, P0507, P0601, P0602 or P1441 are not set.

IMPORTANT: The O2S signal is continuously checked once the above conditions are met.

DIAGNOSTIC AIDS
^ Low fuel pressure
^ Malfunctioning sensor
^ External water on sensor
^ Sensor wire shorted to ground