P0140 - O2 SENSOR CIRCUIT NO ACTIVITY DETECTED (BAK 1 SENSOR 2)

The PCM (Powertrain Control Module) gives 45 volts of reference to the Oxygen Sensor. When this sensor reaches its operating temperature, it begins to generate a voltage, which varies depending on the oxygen content in the exhaust gases.

A mixture generates a low voltage that is below 45 volts, while a rich mixture generates a high voltage, which is higher than 45 volts. The 2 Oxygen Sensors, which are identified by their position in a specific bank, and in this case is number 2, are used to control the emissions.

In addition, the TWC (Three Way Catalyst) is used, which controls tailpipe emissions. The PowerTrain Control Module (PCM) uses the signal received by the Oxygen Sensor O2 to study the efficiency of the Catalytic Converter (TWC).

In case the signal received from the oxygen sensor indicates that the voltage is between 4.25 to 4.75, the PCM determines that this sensor is inactive and the DTC code P0140 is obtained.

• The Check Engine light is on.
• There may be a high fuel consumption.
• The amount of smoke that is expelled from the exhaust pipe is excessive.

An OBD2 code P0140 can be caused by one or more of the following problems:

• The Oxygen Sensor heater circuit may be short.
• The Oxygen Sensor signal may be short-circuited.
• Some cable or connector of the sensor is in contact or in contact with the exhaust.
• Presence of water in some connector of the wiring or in the PCM.
• The PCM may be defective.