P0140

Diagnostic Chart:

Schematic:

When the Heated Oxygen Sensor (HO2S) sensor 2 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.

DTC PARAMETERS
DTC P0140 will set if the HO2S sensor 2 voltage is between 425-460 mV for 125 seconds when:
^ Throttle position is between 8% and 56%.
^ Engine coolant temperature is greater than 40°C (104°F) for 140 seconds
^ Air flow is greater than 5.5 grams per second for 140 seconds.
^ DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0336, P0440, P0442, P0446, P0506, P0507, P0601, P0602 or P1441 are not set.

DIAGNOSTIC AIDS
If a P0141 (heater circuit) is also set repair that code first. An inoperative heater may cause the sensor to cool down, which may cause the inactive DTC to set.

IMPORTANT: Do not apply grease or any material in the HO2S sensor 2 connector or alter the wiring in any way. The wires carry reference air to the sensor used to determine the difference in oxygen from the exhaust gas to the PCM.