The Oxygen Sensor (O2) number 1, which is located in bank number 1, is used by the ECM (Engine Control module) to control the amount of oxygen leaving the engine. This O2 sensor sends a signal to the ECM (Engine Control Module) who uses this signal to adjust the air / fuel ratio. By adjusting the air / fuel ratio, the amount of fuel consumption is controlled as well as limiting the amount of air pollutants leaving the engine. The air / fuel ratio is sent to the ECM as a voltage reading.
The voltage output of the Oxygen Sensor (O2) changes by the variation of gas and air. This change is immediate, for example, when accelerating the vehicle the voltage output must change rapidly, since the air / fuel ratio has changed as well.
The DTC code P0133 OBD2 indicates that the ECM has detected that the Oxygen Sensor (O2) has not made the voltage change fast enough for the air / fuel ratio to change. That is why, this fault code is defined as a "slow response" in the Oxygen Sensor circuit (O2), since the circuit does not react quickly as it should.