P0031 - OXYGEN (A / F) SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)

Code P0031 OBD2 refers to the Oxygen Sensor (O2) located in bank number 1, in the front of the Catalytic Converter. It should be noted that the Oxygen Sensor (O2) that goes behind the Catalytic Converter is number 2.

The function of both sensors is to detect the amount of oxygen in the exhaust gas to compare it with the outside air. All this in order to achieve an ideal fuel or stoichiometric air / fuel mixture, for this the Powertrain Control Module (PCM) adjusts the air / fuel ratio entering the engine.

Its performance is affected when the temperature of the exhaust gases low, for that reason they are equipped with a heating element, which, when activated, helps to make the readings of the Oxygen Sensor (O2) are the most correct.

Basically, diagnostic code P0031 is established when the Powertrain Control Module (PCM) has detected that the resistance of the heating element circuit is below the expected level. Generally, that level of resistance should be below 0.8 amps.

• MIL or Check Engine light on the board.

If the DTC code P0031 has been set, it may mean that one or more of the following problems has happened:

• Cable and / or connectors leading to the sensor may be worn or frayed.
• There may be a short circuit in the heater circuit of the Oxygen Sensor (O2).
• The Oxygen Sensor (O2) heating element may be defective.

The possible solutions before a P0031 OBDII code can be:

• Check all the connectors and cables that lead to the Oxygen Sensor (O2). If you encounter problems in one of these, you can replace them. Similarly, check the proper functioning of the fuse or heater relay in case your vehicle has it.
• Disconnect the Oxygen Sensor (O2) and at the wiring connector, using a digital meter in ohms, verify that there is 12 volts to the power supply of the heating element circuit. It also checks the ground circuit and checks for continuity. It also measures the resistance and voltage of the wiring and compares these readings to the correct specifications. Repair if you find inconsistency in one of these components and if necessary, replace it.
• Change the Oxygen Sensor (O2) number 1.