P0133 - O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)

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.

• Check Engine light on.
• There is a power failure.
• The engine loses power.

The problems that can lead to the establishment of diagnostic code P0133 can be:

• There may be leakage
• Incorrect fuel pressure.
• The Mass Air Flow Sensor (MAF) may be dirty.
• The wiring related to the Oxygen Sensor (O2) can have defects, such as rubbing, broken or worn cables.
• Presence of oil in the Oxygen Sensor (O2) causing the ports that the sensor uses to measure the air / fuel ratio to be obstructed.
• The O2 may be defective.

The steps to diagnose and solve the P0133 OBD II code are the following:

• Check for escape leaks, and if you find them, you can correct them.
• Make sure that the Mass Air Flow (MAF) sensor works correctly.
• Inspect the cables and electrical connection of the Oxygen Sensor (O2), as they may be short or worn. Repair or change as necessary.
• You can check the frequency and amplitude of the Oxygen Sensor (O2).
• Check the O2 sensor, as it may be contaminated or defective. You can replace it if necessary.